A cool pet, if only there was an antidote to it's deadly poison. Thais warned over deadly pet octopus
I've watched a tiny octopus, no bigger than my fist, push a top off an aquarium which was held down by 4 house bricks. These things are deceptively strong. Also they can squeeze through the smallest openings (only their beak is hard, so if the small beak will fit through an opening, the whole octopus will fit. It's amazing to watch.)
Needless to say, getting a blue ring octopus as a pet seems to be almost the same as putting your head in a lions mouth, then flicking his love spuds with a wet towel.