A Mollusk Digimon whose entire body is covered in a mucous-like veil. It is often seen coexisting with other Mollusk Digimon such as Shellmon and Sangomon. It has a very strong awareness of its own territory, defending it fervently from invaders in a desire to protect the Digimon it lives with in symbiosis.
Slimy mucous covers its entire body, drastically reducing its friction when moving. As both strikes and slicing attacks slip right off of it, MarineBullmon's soft body possesses a high defense. Its movements are extremely sluggish, however. It can camouflage itself by slipping into the sandy sea floor, with only its tentacles protruding from the device on its back still being visible. MarineBullmon preys on the foes that enter its territory by dragging them into the sand. If any creature spots a tentacle, it should be wary of surprise attacks from this Digimon.
MarineBullmon shoots a highly pressurized stream of water from its mouth using the Hydro Demolition special move. With Toxic Spread, it shoots a viscous liquid from the tube-like organs hidden in its arms.