So it's no wonder that so many people buy an octo at the pet shop and it dies or lays eggs after a month or two. They've already gone through their normal lifecycle in nature by the time they are collected. The local aquarium shop never does. Heck, they never know what species they have. That's the price of having the neatest invertebrate in the ocean in your living room.
Cuttles are pretty much a cross between squids and octopuses.
They swim around like squids but are very closely associated with the sea floor like octopuses. Some species like to bury in the bottom substrate while other species just sort of sit on the bottom. We can grow them in captivity with no substrate whatsoever and they do fine. But glass bottoms are kind of boring, so we recommend sprinkling a thin substrate of crushed coral or coarse sand on the bottom. Seacuttles really need more tank space than octopuses, and they need horizontal space, not vertical space.