Bryozoa
From Microcosm Aquarium Explorer
Bryozoan colony. Wiki Commons/GNU
[edit] Moss Animals
Number of Living Species: 5,000, mostly marine.
Common Characteristics: Tiny, sessile, colonial animals; form large, variable colonies that may be branching or meshlike.
Noteworthy Behaviors: colonize hard substrates like rock, coral, sand, and mangrove roots; individuals are not interconnected, but typically react to external stimuli simultaneously, retracting into their cases as one.
From: Reef Life by Denise Nielsen Tackett