I had 3 as a kid - Rod, Jane and Freddy. I used to walk down to the fruit and veg shop & get their lettuces that were past their best for free. We were pretty skint. They had an amazing appetite - a lettuce or 2 per day! I kept them in a fish tank, used a fish tank thermostat (NOT A HEATERSTAT), connected to a lightbulb which it switched on & off for heat (probably about 25 degrees C).
I also gave them all the cuttlefsh bones they could eat.
They started laying eggs (in compost) which never hatched, and then one day after cleaning them out, I accidently left the thermostat out of the tank, with the light bulb (heater) inside. They smelt great as they were slowly cooked alive. I was traumatised.
Excellent pets though, provided you don't cook 'em.
I still have the shells somewhere in my mother's house - I think she varnished them.