saddle oyster

/S AE1 D AH0 L OY1 S T ER0/
noun
  1. 1

    Any of a number of bivalve molluscs in the family Anomiidae with thin and translucent shells.

Source: https://en.wiktionary.org/wiki/jingle%20shell, https://en.wiktionary.org/wiki/saddle%20oyster