Worms... sort of regenerate. However, the idea that cutting a worm in half will result in two worms is a myth. Worms do end-only regeneration, meaning they regrow only from the side that has brain or similar. A vertical cut with kill a worm, and a horizontal cut results in one severed corpse, and one regenerating worm, never two worms.You can add worms to your list as well!
Also sharks can replace their teeth. Spiders can replace their legs, and creatures like sponges or sea cucumbers are pretty much cut from some where and now you have two of them types.