Bryozoans (or Ectoprocta) are a phylum of tiny organisms that have lived abundantly from the ancient geological past up to this day, forming large colonies in an aquatic environment, preferably warm. They are often thought of as mossy organisms, but they have calcitic skeletons of a more or less dendritic makeup with which they can form mats over large surfaces.. Actual width of sample is 130 mm, provenance unknown.