The biology of Sequence organisms is rather hard to study, in no small part because the Sequence itself isn’t a coherent species or even lifeform, but a complex amalgamation of several thousand species that has outlived most of its creators, willing or not. Sequence lifeforms belong to “transbiological life”, an umbrella term that covers organisms that, while still biological in nature (i.e bearing obvious characteristics of living organisms and abiding by the constraints of biological metabolism), are mostly indistinguishable from the technology used by the civilisations they have created. The closest humankind has to transbiological lifeforms are vegetal AIs.
As such it is rather hard to determine where a Sequencer ends and where their technology begins — and in a way I am not sure the question itself makes a lot of sense. That being said, Algorab often distinguishes between the two using a criteria of self-modification: if a Sequence organism can rearrange itself and change its purpose on its own, it is an individual, otherwise it is servile technology. Here again the distinction is flimsy, but has the merit of being clear-cut.
Sequence lifeforms are entirely decentralized. They appear as streams of black-grey cells which can link up with each other, exchange information, harden in response to physical trauma and act as tendrils or tentacles to interact with their environment. The cells can specialize into main cells which form the backbone of the individual, and auxiliary cells which form non-vital elements of a Sequencer. Main and auxiliary cells can seamlessly switch between functions within their category, but cannot switch to the other category, at least in observed individuals. Sequencers do not have organs to speak of; their cells can gather into nodes and groups within their bodies but these are not definitive and can change depending on the situation at hand. Due to their ability to produce cells and regenerate entire organs, Sequencers are technically immortal and extremely resistant to damage, though there is a threshold under which an individual cannot come back to full functionality (empirically this threshold seems to be around 10-15% of remaining cells). Sequencers can subsist on carbon-based nutrients and H2O. They have exceedingly well-developed nerve systems, and can feel (or see) in ultraviolet, infrared and possibly radio waves. Their outer surface shows a staggering diversity in colours, geometric shapes and textures that don’t seem to serve any purpose beyond aesthetics.
At first, we assumed that Sequence lifeforms all possessed the same genetic material, but recent autopsies have shown that it is not the case. In fact, while Sequencers all share a common underlying structure, there are at least a dozen different genetic sources in the specimens we encountered in the Serene Sea. Furthermore, these genetic sources came from very different species, some of which had a familiar two-stranded DNA structure while others possessed way more exotic genetics, often based on RNA or silicon DNA. The most likely explanation is that Sequencers as we know them come, in fact, from the various species conquered and absorbed by the empire. It is likely that, at the end of the Sequence of History, newly conquered species were physically altered to become Sequencers in their own right, with their genetic material preserved and repurposed to produce mainstream Sequence cells. Sadly, with the Sequence being in a terminal state, it is impossible for us to observe the assimilation process directly as all remaining Sequencers are fully amalgamated lifeforms. Was the process immediate or spread over several millennia? Was it peaceful? How much of the original species’ identity was kept? Most of these questions are likely to remain unanswered.
**Operational Note 70: Sequence soldiers**
Sequence field combatants are known as shamblers. They are fast, resilient individuals with short to medium-range weaponry embedded in their outer cell layer. Shamblers can infiltrate almost any building given enough time and are impervious to most conventional ammunition. They can also survive small nuclear explosions; untrained personnel is advised to disengage and seek emergency evacuation when encountering a shambler. In the absence of dedicated biochemical weaponry (see Tears of the Forest entry), the most efficient way of tackling a shambler is through the application of sustained, low-caliber fire which is more likely to disrupt its regeneration ability than sporadic high-caliber fire. Expendable railguns such as the ones mounted on Lilac drones are specifically designed for this task.
Sequence combatants that belong to a higher class than shamblers are to be avoided at all costs.
NASA/Caltech, Galaxy of Horrors posters.
Though not universally recognized by the scientific community, the term "pseudotree" is used for remarkable symbiotic lifeforms found on Elora in the Traverse which bear a striking visual likeness to Earth-bound trees despite being radically different in terms of physiology and life cycle.
Nb: the word pseudotree is often used for any plant that vaguely resembles an Earth tree, with the main criteria being the presence of leaf-like photosynthesis-capable parts and a hard trunk. Only on Elora does pseudotree clearly refer to these symbionts.
Pseudotrees have no real Earth analogue. Much like the vast majority of Eloran fauna and flora, they are the result of billions of years of co-evolution between several symbiotes which has led to the creation of multi-species, fully integrated lifeforms. Pseudotrees, in particular, are composite organisms born out of the tripartite symbiosis of three distinct lifeforms: photosynthetic algae, hardened lichens and string-like microfungi. They are, in effect, second-level symbiotes, as one of their components is already a symbiotic lifeform (though pseudotree lichen has lost the ability to perform photosynthesis, it is an ancestral symbiote of Eloran algae and fungi). The three symbiotic species have specialized to the point they are seldom if ever, found alone in the wild. The supporting structure of a pseudotree is made of hardened lichen, almost as resilient as regular wood, that bends and twists to form trunks and branches. This lichen is sustained by photosynthesis carried out via thin transparent sacks containing the algae, as well as complex mycelium networks running in the ground like roots on Earth, extracting nutrients and water from their environment. The entire symbiote is eerily reminiscent of an Earth tree, to the point newcomers can often be fooled into thinking they haven't left the relative safety of arcology gardens while they are, in fact, deep inside the Eloran forest. During Eloran winters the algae sacks retract and dry up to conserve energy,
One of the most notable differences between trees and pseudotrees is that there is no notion of an individual pseudotree. These organisms reproduce and expand through their underground fungal element, which extends tendrils through the soil then emerges to form a small receptacle which is then seeded by algae and lichen spores carried by the wind or by local animals. The link with the parent pseudotree is never broken and as such, there is no meaningful distinction between two adjacent pseudotrees. A lone organism is always an anomaly (usually the last survivor of a lost colony) and a pseudotree forest, for all intents and purposes, is a single, coherent lifeform that exchanges water, nutrients and information across several hundred kilometres by way of sap-like fluids running through lichen trunks. Though pseudotrees do not have neurons to speak of, they possess specialized fungal nodes that synthesize organic compounds and algae receptors capable of "reading" these compounds and adjust the pseudotree's activity, growth and metabolism in reaction to external threats or opportunities. One of the most striking examples of this capability to exchange information is the way pseudotree forests have a self-regulation mechanism resulting in most pseudotree trunks having almost the same mass in a given environment, despite variations in shape and volume. The largest forests are capable of nigh-sapience and react to human presence through colour changes and pheromones which have yet to be deciphered. Limits between colonies are often well-defined and apparently "respected", though sometimes old colonies can end up deeply intertwined, especially on small islands where land is a rare commodity.
Pseudotrees occupy the same ecological niche as Earth tree, as far as ecosystems are concerned, providing shelter, food and resources to a vast number of animal and vegetal species. They are remarkably resilient in the face of infections and physical trauma: contrary to Earth trees, they have a basic immune system and can regrow lost branches or trunks within a few weeks. Their ability to transfer nutrients and water, as well as regulate their growth, makes them quasi-ubiquitous on the planet's scattered continents. Pseudotrees do not seem to have endemic predators or parasites, though they are sometimes targeted by a rather strange lifeform, the Eloran Apple (Pseudomalus Eloriensis), a floating fruit that hijacks the fungal flow not to feed on the pseudrotree but to learn from its synapses and locate the best location for its spores, essentially using the local forest as a vast cartography device.
Pseudotrees are seldom used for human consumption on Elora. As they do not pose any health hazard, their removal is only necessary when a colony encroaches on human gardens or greenhouses, but only has to be carried out once: pseudotrees are clever enough to understand where they can and can't grow, albeit uncontrolled human expansion would very likely trigger more aggressive responses. Pseudotree trunks are awful substitutes for wood: the lichens tend to disintegrate fast without sap flowing through them, and harvested colonies will harden to the point of requiring heavy duty lasers to cut through them.
As far as we know, pseudotrees aren't an invasive organism and can't be implanted on other worlds.