Boxer Crab = Awesome

Taken from Cracked:
FACT: The ocean is crazy as crap. You need look no further than the relationship between the boxer crab and the anemone for proof of that. The anemone isn't just an anus mouthed magic-eye painting, at least not in the hands of the boxer crab. To the crab, the anemone is the perfect sidekick against predators and prey alike. There have been plenty of classic sidekick relationships: Batman and Robin, Kirk and Spock, Holmes and Watson; but the relationship between the anemone and the boxer crab is less like Ed McMahon to Johnny Carson, and more like Rob Schneider to literally anybody that will pay attention to him. See, this sidekick desperately grapples onto the host's body, permanently attaching to its claws like toxic mittens.

Little Mac up there isn't just carrying those pompom anemones; they're actually growing on him. And he wants them there. He has straight up weaponized another animal. Because those precious mittens aren't just for flair, they're going to kill that crab some food. And for their services, the pompoms get some scraps and mobility. The only equivalent we can imagine would be if a whole race of people grafted angry toddlers to their arms, then walked around swinging those babies at would-be interlopers. This analogy especially works if the toddlers are dripping in poison and have dreadlocks.

The boxer crab just wanders around the ocean, knocking motherfuckers out with its poisonous predator fists. So when you lay your head on your pillow tonight, just before you close your eyes, remember this: You live in a world where things that look like a cross between a deep-sea spider and a cobra team up with venomous tentacled sphincters to uppercut poison into all that oppose them.