Grantia compressa is a species of calcareous sponge belonging to the family Grantiidae.

It is a very common species of rocky shores along the Atlantic coasts of Europe from France northwards.

It appears as flattened, purse-shaped vases up to 5 cm long with slit-like oscula at the ends, hanging downwards attached by a stalk to rocky overhangs, often in groups among seaweed.

The entire body of the sponge is pierced by numerous holes, the inhalent pores or ostia.

Development Is indirect with free swimming amphiblastula larva