Sirenfish
Anatomy
Sirenfish are invertebrates in the sponge family of all places. These asymmetrical animals are constructed out of millions of micro-organisms, all controlled by a single organism located in their core. This core organism has a functioning brain, nervous system, and organs, while weaving through the other micro-organisms are nerves that hold them together and send signals to the brain.
Their entire bodies are carved and designed by this core organism. Usually, their anatomy resembles the native environment as a method of camouflage, and most of the time they are specially designed to fit their particular climate. Sirenfish living in coral reefs and coral environments are slimmer and have bendier bodies, to fit themselves in large caves, cracks and crevices.
Diet
Sirenfish are an apex predator, sat at the very top of every single Exio food chain. Sirenfish have been known to consume almost every single other species of animal on the planet, however individual sirenfish can only consume certain species based on their physiological structure.
Some sirenfish are designed to swallow large prey, digesting them in large vats that serve as stomachs. The digested food is distributed to every single micro-organism that makes up the sirenfish's body, including the core organism. Other sirenfish are filter feeders; as they swim through the oceans of Exio they are constantly taking in nutritious food, keeping the micro-organisms constantly supplied.
Reproduction
Sirenfish reproduce asexually. Throughout roughly 300 Exio years, the core organism will be slowly copying every single one of their cells. At the end of each reproductive cycle, the immature sirenfish core organism is disposed of; it is taken out of the body through a special tube that all sirenfish have, made of micro-organisms.
Behaviour
Sirenfish are quite docile when confronting sophonts. For an unexplainable reason, sirenfish are generally quite inviting, encouraging any visitors they've ever had to Exio into their primitive villages and offering them gifts.
Sirenfish have the most incredible communication of any species in the Yonderverse. They have a deafening, siren-like voice that can be heard from a handful of other planets in the Ueran System.
Settlements & Civilisation
Sirenfish houses are constructed with the same micro-organisms as their own bodies are. These ones are dead, however, and require no maintenence. When dead, these micro-organisms become extremely firm and produce an odorless, colourless and tasteless substance that sticks to others of their kind. This makes it incredibly easy for these houses to be built.
These houses make up countless villages, towns and cities across the Exio Rings. The houses are all built individually and are not build in a communal design, but are instead built with a many metre radius around for future expansions. Sirenfish choose practicality over personal interest, and each house possesses only the basic necessities for a sirenfish, with zero items of any person value.
Interplanetary Communication
Sirenfish have a total population of 0 outside of their native planet. They are unable to survive outside of their native environment, and so they have made no attempt to leave their planet. They are completely aware of life beyond their planet, and are even able to communicate.
Their siren screams are detected by a local space station, which are translated into hundreds of languages and are sent to whomever the sirenfish are attempting to communicate to. Those people then send a message back, and the space station is able to translate it into their sirenfish language, which is sent to the sirenfish in Exio.
Intriguing. And beautiful. And horrifying. And all of that combined.
Sirenfish are the whole package xD