Echinoids

Acrosalenia hemicidaroides from Neufchateau Vosges, France, Jurassic, Grand Oolithe Layers ,Bajocien Superieur Formation -together with spines. Actually, also in this wonderful specimen (which weighs 8 lb!), are tons and tons of crinoid stems.







(Micraster) Encope Tamiamiensis
Pliocene
Charlotte County, Florida

Irregular sea urchins are bileraterally symmetrical and are streamlined for burrowing in soft sediments. Burrowing sea urchins are found in Cretaceous shales as entire body fossils.