I Love Whelks. Yes, I know they're rubbery, and look like your worst nightmare, but they are delicious.
The ones above were bought ready cooked, but they are also readily available here live. I once made the mistake of buying live Whelks, thinking they were cooked; not so difficult, as they look much the same. They were a bugger to get out of their shells, were unbelievably chewy, and they didn't really have the flavour I'd expected. I munched my way through several, probably screaming, Whelks before I realised my mistake. Oh how we laughed!!!
Nowadays I always make sure they're ready cooked.