This species of scallop is often covered with the symbiotic sponge Myxilla incrustans or Mycale adhaerens. The symbiosis is likely mutualistic. If one of the major predators of the scallop, Evasterias troschelii, encounters the scallop (and the scallop does not swim away) it often turns away if it touches the sponge; likely in response to some secretion or to the spicules from the sponge. The sponge also appears to make it more difficult for the seastar's tube feet to adhere to the scallop. If the sponge is removed from the scallop and the scallop is prevented from swimming, it is readily captured by the seastar. The scallop will also swim from predators of the sponge, such as Archidoris spp, so the sponge is benefited as well. The swimming scallop may also help carry the sponge into areas with clean water and good currents, nd help prevent fouling of the sponge.