Notes: Whelks are the largest snails in this area. Related Lightning Whelk grows to 16", and is sometimes called Conch and eaten as such. Whelks prey on bivalves by drilling through their shells.
A large ( and filthy ) whelk feeding on something. The head end is to the left.Upended and fully withdrawn, showing the operculum which closes off the shell. This individual was about the size of your hand. Note the curious puffer fish at upper-right.The somewhat smaller Waved Whelk Buccinum undatum is a scavenger
The Essentials of Deeper Sport Diving John Lippman AquaQuest, 1992 320 pages, illustrated, b&w
This book is not about technical diving but covers many important aspects of decompression physiology and deep-diving techniques and equipment that any diver ought to know. I see it for 1 cent used on Amazon - get a copy !!!