The oval-shaped body belongs to a marine flatworm, a group of invertebrates that can range in color from see-through to neon and seemingly glide along the bottom with hairlike protrusions all over ...
You are probably referring to the land planarian, a.k.a. hammerhead worm, a soft, slimy, yellowish worm with black stripes down its body and an arrow-shaped head. This common nonnative flatworm ...