Eutylus cuneatus was a piddock, one of the specialised bivalves adapted for life inside a self-made burrow in a firm substrate. Like living pholadids, it probably used repeated shell movements to work into the substrate while the soft body remained protected within the cavity.

Once established in its burrow, it would have fed by filtering suspended organic particles from seawater. The exact substrate used by this fossil species is not preserved in the shell itself, so details of its boring behaviour remain an inference from its pholadid relationships.