Strombus grazes on algae. Rapana bores into live bivalves, though it probably would accept other prey if it can catch it. Busycon is also a predator/scavenger. It preys on bivalves by wedging them open with the outer rim of the aperture. I had one in a tank that broke a Mercenaria shell in this manner rather loudly.
Dr. David Campbell
"Old Seashells"
Biology Department
Saint Mary's College of Maryland
18952 E. Fisher Road
St. Mary's City, MD 20686-3001 USA
[log in to unmask], 301 862-0372 Fax: 301 862-0996
"Mollusks murmured 'Morning!'. And salmon chanted 'Evening!'."-Frank Muir, Oh My Word!