Moss Animal

The Bryozoa have a long history. From the Lower Ordovician (500,000,000 to 430,000,000 years ago) onward, most limestone formations, especially those with shale alternations, are rich in bryozoan fossils. The skeletons of calcified bryozoans are easily preserved. Stenolaemates are abundant fossils; after their appearance in the Upper Jurassic (140,000,000 years ago), cheilostome fossils also are abundant.