Glatzin is a strange one. Technically only humanoid by choice, he is a colony of macro-cellular cells or similar structures capable of reforming and reshaping almost any way imaginable baring a requirement of conservation of mass (he can cheat this mildly by making hollowed out structures inside him with support beams, etc). His entire body counts as his mind with a hidden central communication network inside his cellular structure allowing command cells to coordinate all the remaining cells while still allowing them to function relatively independently on lower levels. This gives him the ability to be split apart, change shape, etc without taking much, if any, actual damage (similar to a water hydra).
This also, however, leaves him with less than the best of memories despite being good at making calculations. This was later "fixed" by his finder in his origins. His origins are still in the works, but was likely recovered off an asteroid by a human research team where he began to mimic a similar shape to them out of curiosity once being modified enough to begin to form his first memories
He has also "stolen" some traits from images he'd "seen" throughout the lab he was kept in, such as flukes on his tail. Despite being able to shapeshift he does have difficulty understanding the anatomy of another creature, and unless given a "thorough" inspection of it he will often mimic incorrectly. For example, if he were to take a feminine form the nipples would likely take the form of smaller maws. Same with any other openings as this is the only "opening" he understands having.
He's very smart (although somewhat full of himself), but incredibly curious, and tends to act quite silly as others enjoyment makes him feel safe.