I didn’t know what it was. I had to read the comments. It’s extremely toxic/venomous. More than anything on land. It’s not aggressive, but its small and beautiful and lives in shallow water. (Blue ringed octopus)
It looks like a baby blue ringed octopus. They’re poisonous and there’s no known antidote if you get bitten. The person holding it in the photo probably doesn’t know any better. We were warned about them when I took scuba diving lessons. I’ve never seen any on the scuba diving trips that I’ve made. For a mouth, cephalopods (octopus, squid, cuttlefish) have a parrot like beak at the center of all its legs.