Found this on the beach by Carrolls Point a few weeks ago.
According to this link, it seems it is the Cipangopaludina chinensis, or Chinese Mystery Snail. It claims that it is found only in Lake Ontario. However one that it appears to be is the Japanese Mystery Snail, even though the above link claims that it is found only in Lake Erie. Since neither of them is actually native (both are from Asia) I don’t think it’s beyond the realm of possibility that they can appear in either Lake. The striations on the Japanese one make it look more like this one.