These crabs can crack a coconut in one swipe; but they're generally too slow to be very dangerous to humans.
Giant Isopod (below)
If you're afraid of bugs, you're really not going to like the Giant Isopod. It resembles nothing so much as a cockroach the size of a guinea pig, but it's actually a crustacean related to shrimp and crabs. These scavengers roam the cold, dark sea floor from 560ft to 7,000ft below the surface of the ocean, eating mostly dead whales, fish, and squid.
Naked Mole Rat
Its wrinkled pink skin, piggish nose and protruding teeth don't exactly make the naked mole rat the cutest animal around. Colonies of these hairless rodents live in underground palaces led by one dominant rat the queen, which is the only female to breed and bear young. As with bees, naked mole rats have roles in the colony, including workers that dig the tunnels and gather food. Most naked mole rats are found in the sandy deserts of sub-Saharan Africa.