thumb|right|Holes made by clionaid sponge (producing the trace Entobia) after the death of a modern bivalve shell of species Mercenaria mercenaria, from North Carolina thumb|Close-up of the sponge boring Entobia in a modern oyster valve. Note the chambers connected by short tunnels.
thumb|right|Holes made by clionaid sponge (producing the trace Entobia) after the death of a modern bivalve shell of species Mercenaria mercenaria from North Carolina thumb|Close-up of the sponge boring Entobia in a modern oyster valve. Note the chambers connected by short tunnels.