Bryozoa

: Zooids secrete a protective chamber called a zooecium, which can be gelatinous, chitinous (like insect shells), or calcified (like coral).

, commonly known as "moss animals," are a phylum of microscopic aquatic invertebrates that live in sedentary colonies. While they are often mistaken for coral, seaweed, or even gelatinous "blobs," they are a distinct group of filter-feeders found in both marine and freshwater environments. Biological Structure and Anatomy bryozoa

: Each zooid has a "crown" of ciliated tentacles called a lophophore used to filter food like phytoplankton and bacteria from the water. : Zooids secrete a protective chamber called a