Acquired by Evans in 1894 from near Phaistos. Although he describes is as Tridacna, a Red Sea shell, in the printed catalogue, it is more likely to be Spondylus shell. It is difficult to date but is probably Middle Minoan (2000 - 1600 BCE).
Bibliography
Evans, Arthur. 1928. The Palace of Minos at Knossos, II, pp. 45-46, fig. 21
Myres, John (ed.). 1936. British Archaeological Discoveries in Greece and Crete 1886-1936, p. 27
Brown, Ann. 2001. Arthur Evans’s Travels in Crete 1894-1899, pp. 404-405