Micraster

Micraster was a genus of extinct sea urchins that lived around 130 million years ago during the Cretaceous period. As echinoderms, they had a rounded, spiny shell called a test, which was often flattened and bowl-shaped. Micraster fossils are commonly found in marine sediments and provide valuable information about ancient ocean environments. They were slow-moving bottom dwellers that grazed on algae and small particles on the ocean floor. Their distinctive shape and abundant fossils make Micraster important for understanding marine ecosystems of the past and for dating the rocks in which they are found.