Depending on which tavern of drunk sailors you ask around in, Powder Monkeys - also known as Huokan Monkeys, Fire Chimps, Dragon Monkeys, and Skinflint's Bane - are alternately feared, loved, or dismissed as a complete fairy-tale.
The least fantastic version of the 'powder monkey' is a creature found on a small cloud island, by a ship that stopped to make minor repairs. Apparently, the island contained a species of bright orange-red monkeys, constantly yelling at each other (and the intruding sailors) and throwing…waste product. Supposedly, one of the crew, an alchemist kept samples, and found that when he used it in his gunpowder mixture, the result was nearly as good as Koldun Blue. The island, of course, has never been exactly located.
Of course, this is the most tame version - others will say that the monkeys eat (or excrete) gunpowder directly, that they have powers like Dragon Koldun, that they can set off gunpowder by their presence - or, instead, keep it from setting off - or, maybe, they just like gunpowder, and can be trained to distribute it to your crew.
Travelers' Comments on Powder Monkeys
While I was serving on a Royalist merchant ship (not by choice, mind you), the first mate purchased what a humble merchant assured him was a genuine Powder Monkey, which would ensure that our supply of gunpowder wouldn't get excitable and send us all piecemeal to the Cerulean. That little terror had the habit of eating or throwing overboard everything it got its hands on, but the mate kept defending it. Eventually, of course, the paint began to wear off of the monkey's fur. We ended up marooning the mate and the monkey together.
— Warren the Hapless