Discover how horseshoe crabs have lived in the ocean for 300 million years. Learn all about the giant clam - the largest shellfish of all, which can live for 100 years. This book takes you on a magical journey through some of the wonders of our oceans.

"DK Smithsonian" at head of title. Content previously published as "The Rock and Gem Book" in 2016. Includes index.

Shells -- Tuns, winkels, and relatives -- Conchs and cowries -- Unusual mover -- Augers, cones, and turrids -- Whelks and relatives -- Murexes and relatives -- Other snails -- Floating the waves -- Clams, cockles, and relatives -- Oysters, scallops, and relatives -- Strange shells -- Nature's submarine-- Index and acknowledgments.