Some ancient echinoids, ophiuroids, and asteroids had slipped the bottleneck and coexisted with the ancestors of modern - day sea urchins, brittle stars, sand dollars, and relatives, for many millions of years. (sciencedaily.com)
Note that molluscs, foraminifera, and echinoids contribute < 2 % at all sites and are not plotted. (pubs.geoscienceworld.org)
Smaller holes in the surface of the reef are the result of boring organisms such as the spiny echinoids (sea urchins) and the boring mollusks. (ambergrisCaye.com)