FAMILIES : ?
Species?

Sponge barnacles are a specialised group of barnacles that live within their sponge
hosts. The correct classification for these animals is far too complex for me so I
will just leave them under the title Sponge Barnacles!
This empty shell was found in a dead sponge on Brunswick Heads beach.

Below is a seperate species also found in a dead sponge on the beach.

This, below, is a basis (base plate)for yet another species, found on beach.