They say it takes all kinds.
In this case, "all kinds" is rather unusual. The Cyanos, also known as "Plankton People" or "Algae Swarms" (or occasionally Bioswarmanoids) are an interesting subculture which blends the rules between infomorphs, exhumanism and microscale morphology in aquatic habs. Experimentation in different morph sizes is possible - The Colony (p. 88 Sunward) is an example of a hab which uses microscale morphs (run through distributed or external computing) to conserve on space, and offer entertainment. Swarmanoids themselves are a exotic morphology using microbots and segmented, distributed computing which can host even multiple egos. Smart Plankton is another aquatic nanotech, similar to Smart Dust, which can do various forms of recording and processing.
The Cyanos push a lot of this tech even farther, forming an unusual subculture. They utilize biodrones embedded with nanotech-assisted computing to form an organic swarm of otherwise independent microorganisms in concert, forming a kind of living swarm akin to planktons or algaes. The name comes from "cyanobacteria", a photosynthesizing, aquatic microbe. A normal Swarmanoid can already support more than one Ego, though by configuration only one normally has physical control of the morph. Cyanos and their plankton swarms utilize larger formations and denser swarms to allow more egos to exist in the same space, blending swarm composition and the biological neural substrate of something like a Hamilton cylinder, which acts like an Infomorph server.
Actually operating in a plankton swarm is an interesting experience. It blends normal operations such as in a server with greatly diffused sensory information. All egos operating in the swarm share the same sensory inputs (though some can filter accordingly), and because they are all distributed in the same computing space, sharing thoughts, memories and information is incredibly easy, similar to something like Linkstate or Nimbus' Hyper-Mesh Insert. Thus, Cyanos tend to be very communal or "hive" minded, and are known to act less like individuals and more like components of a whole - even when outside the swarm they may say "we" instead of "I". Some Cyano colonies even integrate nanotech similar to the Ego Bridge, so they can skim minds of bimorphs to share, or even fork them directly into the swarm - but the invasiveness of this prospect means they do not engage in it without consent.
The swarm itself has limited mobility, and limited defenses. While they can move, this requires concentrated effort from multiple individuals, and is difficult to do against currents in the water. For defense, Cyanos rely on guardian nanotech being near them, or integration of nanophages into the swarm. Some have gone toxic to prevent local aqualife from trying to prey on them (and luckily the small amount of extant Neo-Whales makes the issue of sophontophagy relatively non-existent). But, due to the relative small size and the fact that most Cyano communities are very peaceful and open means they have little to fear. Most communities spend their time sharing experiences, debating things or collaborating on projects on the local mesh - while they also digest sensory information and autonomously gather resources from the surrounding water. Due to distribution, Cyano swarms can work on things very quickly, and with a large enough area can contain dozens of Egos in a discrete swarm.
Cyano communities are naturally limited by the fact that their micro-biodrones are aquatic only. They are most populace in Atlantica and inside certain flooded habitations on Ceres and Europa - but do not prefer the latter two's open oceans as they lack light, heat and can be difficult to be secure in. Due to their communal nature, they often fit in well with Cetacean uplifts, some of whom work to "shepherd" cyano swarms from any aqualife which might try to ingest them. Small colonies exist elsewhere in the system, of course. There are a handful of Cyano swarms recognized as citizens in the Titanian Commonwealth, at least one biodesign corp on Enceladus entirely formed by a Cyano swarm - and several algae swarms have interests in gatecrashing, exploring aquatic exoplanets. When they exist in more capitalist societies, Cyanos often get what resources or allowances they need by working as think tanks, programmers, consultants or software designers - their unique headspace able to come at problems from multiple angles simultaneously. They also can make interesting teachers or tutors, filtering a single bit of information through multiple Egos rapidly to find the best way to communicate it. Due to this unique mindspace, however, many Cyanos have difficulties acting as individuals, similar to the Synergists. They may experience a form of "withdrawal" when instanced away from the swarm, or have difficulty in social interactions.
Sleeving into a Cyano "plankton swarm" is more like using an Infomorph server than a real morph (though does still require an Alienation and Integration check at -30 for Exotic morph, typically) as physical motion of the swarm is limited and more akin to interfacing with bots than moving a limb. The Cyano medium does not run Eidolons, but an Ego distributed onto the Swarm retains individual software plug-ins and upgrades. As it it highly distributed, the Aptitude Maximum for the swarm is 40, but due to semi-biological neural media Cyanos are immune to traditional brain hacking - at least from outside the swarm itself.
Plankton Swarms blend the rules between swarms and servers. They operate under standard mechanics for Swarms, as per Transhuman and X-Risks. In their standard volume, they can hold 5 Egos normally, and have a DUR of 30. Each additional "unit" of swarm adds 15 DUR and doubles the amount of Egos the swarm can hold. Should they need to move, the swarm has a speed of 2/8 Submarine, but take -30 to Swimming tests to oppose strong currents, and may even be damaged by them as a normal swarm would be Wind. The physical swarm comes equipped with 360 Degree Vision, Enhanced Hearing, Mental Speed and naturally Swarm Composition normally, and can be equipped with any Swarmanoid only enhancements (as cyberware) and bio, cyber or nanoware allowed to Swarmanoid morphs as seen in Swarmanoid Enhancements (p. 213 Transhuman). Additionally, the way the swarm is constructed means all egos in it gain a benefit akin to Parallel Processing, offering teamwork bonuses automatically and granting +5 COG to all users, but reducing TT by 1. Typically, Cyanos add Nanophages, and some combination of Eelware, Injectors or Poison Glands for defense.