Trachynemites

Trachynemites one of the few known fossil jelly-fish. It belongs to the order Trachymedusae, the members of which have absolutely no hard parts in their bodies; they cannot, therefore, under ordinary circumstances, be preserved as fossils. Impressions of the body have, however, been left in the fine mud, winch has consolidated into the "Solenhofen slate" of Germany.