Well Preserved Diagoniella Cambrian Sponge Fossils Assemblage

Diagonella belong to the family Protospongiidae, which were a group of early and primitive sponges of the Class Hexactinellida. Diagonella were 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

Reference: The Fossils of the Burgess Shale by D. E. Briggs, et al.