Fossil Sponge And Trilobite Association from Utah

Description: Diagonella belongs to the family Protospongiidae, which was a group of early and primitive sponges of the Class Hexactinellida. Diagonella was attached to the sea floor by long spines at the base of the sponge. These spines are rarely preserved. The six-rayed spicules were not fused into a net, so were relatively fragile as a result. These sponges are very rare in the Burgess Shale of British Columbia, and sponges are relatively uncommon in the fossil record owing to their delicacy. This specimen exhibits unusually fine preservation . The associated trilobite is a detailed example of the trilobite Elrathia kingii. These trilobites are often found with disarticulated or missing free cheeks, as is the case here, but the stark contrast in coloration to the matrix and the association with the uncommon sponge makes for a most desirable specimen.