The archaic sponge reef-dwellers of the Cambrian gave way to bryozoans—tiny, group-living animals that built coral-like structures. Ordovician reefs were also home to large sea lilies ...

Research into the Ordovician period also revealed a significant increase in bioclaustration diversity, which involved organisms like bryozoans and corals. This phenomenon, termed the Ordovician ...

Previous reef-builders such as bryozoans were joined by corals and ... over the South Pole but the vast icecaps of the late Ordovician period melted almost to nothing. Sediments formed from ...