Giant Isopods are a type of Bathynomus isopod that, compared to other isopods, are really big. Of those so far fished from the deep seas, they have been found in sizes of up to 30 inches in length, mostly discovered at depths from around 1200 to 2400 feet. They have eerie eyes compounded at around 4000 facets that are very reflective. Chances are, larger ones lurk in the depths, snacking on whale carcasses and ready to scare the bejesus out of submariners.
Like the pill bug, they curl up into a ball in defence, meaning that you and a friend with ROV's could get an extreme game of underwater croquet going.