Stomatella sp. – False Ear Shell – ヒメアワビ – size small
Stomatella is a genus of snails that look like small abalone. They are more closely related to top shells though. They are small and fast (at least for snails)
The snail here was found under a rock and I have found a few pictures that look very much like this. They are not identified as the same species of Stomatella though. Amami 2026
The other side of the Stomatella. Amami 2025