20" Starfish Fossil Plate (with stand)Sea levels were at their highest levels of the Paleozoic Era during the Ordovician Period and saw water temperatures of more than 110 F. These conditions allowed marine life to flourish and led to wide diversification. It is during this time that sea stars (from the class Asteroidea) and brittle stars (from the class Ophiuroidea) diverged. Sea stars, or starfish, tend to have legs that are wider and more connected to one another. They had tubular feet