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The Clypeus Grit can be found along this stretch of the trail. The Clypeus Grit is a type of limestone that formed around 170 million years ago in Middle Jurassic times. It is particularly interesting because it contains lots of fossil sea urchins, or echinoids, of the species Clypeus ploti.
Clypeus ploti
Clypeus is a type of irregular echinoid. Irregular echinoids have a strong bilateral symmetry, unlike the regular echinoids that are round and have a radial symmetry. Irregular echinoids live in burrows in the sediment on the seafloor, and burrow and eat their way through the sediment to get nutrients. Clypeus had spines, but their spines would have been more like hair. Because irregular echinoids stay in the sediment, they didn't need the spiky and sometimes poisonous spines that the sea urchins we can see on the seafloor today have for protection.
Some things to look out for if you find a Clypeus.
Clypeus fossils were often called 'pound-stones' because in the past they could be used as a measure of weight because of their very regular size and mass.
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