mytilus galloprovincialis and sea sponges in underwater caves in bulgaria

black sea bulgaria fauna animal benthal benthos bentos biofouling biology ecology filtration filtrations haliclona invertebrate invertebrates life marine overgrown porifera saltwater biological sessile sponge sponges spongia water world wild wildlife aqua diving mediterranean seaside spong spongea yellow mussel mytilus mollusk mytilidae shellfish bivalve mollusca seafloor ecosystem mollusks mollusc seashell galloprovincialis