Japanese Ivory Shell/Japanese Babylon Shell are known as Bai, Baigai, Isobai in Japanese.
They are just in season now as we see them over the counters from Spring to Summer.
They used to very common and found all over Japan, but unfortuantely too many have been caught or killed by pollution in recent years.
The biggest specimens are caught off Toyama fairly deep where they can attain 15cm length and weigh as much as 300g.

The most popular way of eating them is to first boil them in water and soy sauce and serve them cold.

But the Japanese apprecaite them very much raw as sashimi and

sushi!

There must be a good reason for the Japanese to call them “Kai no Oosama/King of Shelfish”!