Hard Dorset limestone made from shells and snails is called Coquina.

Coquina is a type of sedimentary rock that is formed from the accumulation and cementation of shell fragments, particularly those of marine bivalves and gastropods (snails). The term "coquina" comes from the Spanish word for "cockleshell."

While Coquina can be found in various locations, the specific formation in Dorset, England, is known for its durability and beauty.