Bryozoa range from the Ordovician to Recent, possibly also in the Upper Cambrian. Also called moss animals, all are colonial, but their colonies, wether living or fossilized, are easily overlooked. Bryozoans may be massive, encrusting, branching or sheetlike. it has a planktonic larval stage, where the larva lands on a firm substrate, buds, and starts a colony. The photo at left shows a Bryozoan colony in the upper left hand corner. Each animal in the colony is surrounded by a membranous or calcareous sac, called a zooecium. The animals feed by protruding small tenticles through holes in the sacs by internal fluid pressure. Below, A colony free of surrounding sediments and a colony insitu.
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