Sluggy the Unshaven

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

In Sluggy's open-air room is an Egg-Plant. However, it's at the very edge of the room. Once Yoshi has collected enough eggs, the player must lob eggs at the slug's skin. Every time an egg hits the skin, the skin will be pushed back and the egg will bounce off. Yoshi can then pick up the egg and lob it again. Once the skin is pushed back enough, Yoshi can shoot Sluggy's heart. Much like Naval Piranha it is possible to see the boss before Kamek magically alters him. Unfortunately, the player can't destroy Sluggy before Kamek appears.