Imagine if you were out on the beach with a girlfriend.... She lays down the towel, demands you to cream her up, then falls asleep in the sun....
You wander off to check out the other babes/do whatever. Come back to the girlfriend and this crab is hunched over her bloodied corpse,decapitated head in the crabs claw. You attack it but its thick shell provides too much protection for your whimpy human strength, so it scuttles back into the sea with its snack.
Would be a nifty horror movie! I'm suprised sci-fi hasn't made a "mutant crabs" movie yet. God knows they have horror movies about every other animal in existance
Would rather watcha a hoarde of giant crabs killing beachgoers in a crab invasion, then "megladon vs giant squid"