Smoky Progg

The Smoky Progg is a hidden boss in the first Pikmin game, and is possibly the toughest. The only way to encounter it is to go into the The Distant Spring area before day 15. It will be in the mass watery area on a later-useless mound of small islands in an egg form. After its health is 1/2 drained, it will break out of the egg and show its true form; a black, slimy frog-shaped creature made of tar with glowing yellow eyes. It will follow you back to base, so it's necessary to kill it. The only way to hurt it is to throw red Pikmin onto its face. Any Pikmin left walking in its trail will succumb to the tar. It has an incredibly high defense, and takes a while to kill. It will be worth it, however, because it will drop a brown pearl when killed that will be worth 100 Pikmin for any Onion that it gets into.