These specimens are the egg cases of the Channeled Whelk. The Channeled Whelk is a species of large predatory sea snail. The egg cases of a Channeled Whelk are commonly called a "Mermaid's Necklace." The egg cases are stringed together and the strings range in size from 5 - 14 cm long and 2 cm wide. The individual egg case ranges in size from approximately 1.5 - 2 cm long and 1 - 1.5 cm wide.