It's a Ramshorn snail hun , perfectly safe but prolific breeders and you could end up with lots - especially if you accidentally over feed your fish
You can sell them or give them away though if you do start to get over run .
I'm not worried about it reproducing, it's in an aquarium alone supposedly cleaning the gravel. I'm sure my clown loach would like a snail snack should I end up with more.