" But Wilson was ahead of the curve. Long before the first octopus-enrichment handbook was published, many octopuses ago, he set out to create a safe toy worthy of an octopus’s intellect. Working at his lab at Arthur D. Little Corp., Wilson devised a series of three clear Plexiglas cubes with different locks. The smallest of the three has a sliding latch that twists to lock down, like the bolt on a horse’s stall. You can put a live crab—a favorite food—inside and leave the lid unlocked. The octopus will lift the lid. When you lock the lid, invariably the octopus will figure out how to open it. Then it’s time to deploy the second cube. This one has a latch that slides counterclockwise to catch on a bracket. You put the crab in the first box and then lock it inside the second box. The octopus will figure it out. And finally, there’s a third cube. This one has two different latches: a bolt that slides into position to lock down, and a second one with a lever arm, sealing the lid much like an old-fashioned canning jar closes. Bill told me that once the octopus “gets it,” the animal can open all four locks in three or four minutes. "
― Sy Montgomery , The Soul of an Octopus: A Surprising Exploration Into the Wonder of Consciousness