Crumillospongia is a genus of middle Cambrian sponge known from the Burgess Shale

Burgess Shale

The Burgess Shale Formation, located in the Canadian Rockies of British Columbia, is one of the world's most celebrated fossil fields, and the best of its kind. It is famous for the exceptional preservation of the soft parts of its fossils...

 and other localities from the Lower and Middle Cambrian. Its name is a reflection of its similarity to a small leathery money purse, or Crumilla (L.). That is, it has a saclike shape, and its wall has holes of two sizes, with a well-developed internal canal system.