Sand collar

Sand collar from the moonsnail Neverita josephinia and shell of that species on the right, Mediterranean Sea
A somewhat damaged sand collar of Euspira catena. When the light is shining through the collar, it is possible to make out the individual egg capsules within it.

Sand collars are the characteristic egg masses of one family of sea snails, the moon snails, marine gastropod mollusks in the family Naticidae. These egg masses are often found washed up either whole, or sometimes in fragments, on sandy beaches where moon snails are living, either intertidally or subtidally.