Thin-ribbed Cockle (Fulvia tenuicostata)

This was one among many shells on the shore however, it had a neatly drilled hole with beveled inner edge on the part where the cockle would have been most fleshy. I found a few of these shells with holes as I walked along the shore. Investigating further, I found that these holes were made by the predacious Sordid Moon Snail (Polinices sordidus). Although I could not find the snail I found tracks on the sand. The snail would have drilled through the cockle shell and feasted on the flesh within.
My next spotting shows the egg mass of this snail, a common sighting in these parts.
http://www.jungledragon.com/image/36896