I wrote about this snail, Melongena corona, in a recent post. After I took pictures of its foot and siphon, I put the snail down on the wet sand. It immediately started crawling back to the sea. In the picture, you can see its track behind it (the snail was moving to the left). The transverse ripples visible in the snail's track are probably caused by the waves of muscular contraction that travel along the sole.
One interesting thing I have been noticing about these intertidal marine snails is that if they find themselves outside of the water, they don't just "panic" and withdraw into their shells waiting for the water to return. Most seem to start crawling towards the water and eventually reach it (if they are close enough to it, of course).
Their behavior seems to be a preadaptation to living outside of water. Presumably, the marine ancestors of those snails that later evolved to become terrestrial had behaviors similar to those of M. corona and other snails that live near the edge of the sea.