What is "crumillospongia"

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