So there you are, innocently suveying the ocean floor using one of those nifty remote-controlled unmanned submarines. At the end of the long day, quittin' time rolls around, and you reel the machine back in. And then you discover that it has acquired a passenger, and the passenger is one of these:
I mean look at that thing! It's three times the size of Nefertiti! And its feet - that monstrosity could seriously injure you by stabbing you with its feet!! Think about that for a sec - its legs, of which it has far too many, end in seriously sharp points!! And it's wearing armour!! What the hell, Earth's Oceans, what the hell?!
Anyway, it's a fairly common critter, a species of giant isopod which scurries about the ocean floor, feeding on large dead things and slow live ones. Its scientific name is Bathynomus Giganteus.
For the record, I think it's about the niftiest thing I've seen all day. And I am so making a D&D monster out of it.