Sluggy the Unshaven

Sluggy the Unshaven is massive monster found in Super Mario World 2: Yoshi's Island, resembling a see-through blob with a face, hair in various places and a visible (and equally hairy) heart. To defeat Sluggy, Yoshi had to throw eggs at his heart, pushing through his gelatinous skin. He was originally a tiny, untransparent version of himself, until Kamek used his magic on him.