Predator and prey

 

This is the predator - Bladder Moon Snail Neverita didyma

And these are the prey - check out the signs of homicide.

Moon snails use a rasping tongue (radula) plus acidic secretions to dissolve and scrape a neat circular hole on their prey.

So next time you see these shells with neatly circular holes, you know they died as prey and then got washed up.  

Marine homicides.

Imagine - the prey, cannot do anything - its defence (the shell) has been bored through.  

Oh, Moon Snail, not so benign are you?