Sycon raphanus is a species of marine invertebrate, a calcareous sponge belonging to the family Sycettidae.

They are filter feeders, maintaining a flow of water through their structure which passes out through large openings called oscula.

This small purse sponge grows singly and is globular in shape, sometimes with a short stalk.

This species closely resembles Sycon ciliatum but can be distinguished by the fact that the choanocyte chambers are fused.

It is found low down on the shore and in the neritic zone down to about seventy metres, in caves, amongst seaweed, under stones, in rock pools and on vertical rockfaces.