Interesting. While we're off topic, they're also delicious. Slightly sweeter than squid and I find less prone to going tough. They take a little bit of preparation but you get quite a good size meal out of a single one. As a bonus they grow quickly so are a fairly low impact species to take.

Yeah, I can't eat anything that smart, like this or an octopus.

Is it smart though? As in, is it actually thinking or is it simply acting on impulse/reflex/instinct?

I wouldn't eat them either, but clearly they have no problem with eating their own kind.

They are also used as a calcium supplement for animals:

"Today, cuttlebones are commonly used as calcium-rich dietary supplements for caged birds, chinchillas, hermit crabs, reptiles, shrimp, and snails. It is not for human consumption"

https://en.wikipedia.org/wiki/Cuttlebone#Human_uses