Bryozoa are invertebrate animals that can be either in tubes, branch or encrusting, exclusively marine. They are all living in sedentary colonies, not a group of social individuals, but individuals that shares vital functions. An individual is sizing about a millimeter. ## Morphology What we see underwater isn't one animal, but a colony of animals, that create a rigid structure. This is a Bryozoa.  ## Anatomy An individual is name a zooid, made of a cystid and a polypide. The polypide is the animal and the cystid is the kind of exoskeleton making the outside of the animal and making the "logettes". They have a rectractile panache that is out when they are in nutrition phase. They're considered as "ectoprocta" because they have their anus outside the skeleton. This is the realm they're from.  ## More : <iframe src="https://en.wikipedia.org/wiki/Bryozoa" width="100%" height="800"></iframe>