THREE FOSSILS AND AN ECHINODERM FOSSIL GROUP IN MATRIX Including a Diacalymene fossil trilobite, 5.3cm long; a Terebratula fossil Brachiopod 6.4cm long; and a Gryphaea mollusc fossil, 2.9cm long; the echinoderm fossil 20.5cm wide, (4) Footnotes: Echinoderms are marine animals from the Echinodermata phylum and include creatures such as starfish, sea urchins and sea cucumbers, They first appeared in the geological period known as the Cambrian Period, between 541 and 485 million years ago.