Watch List notes:

BOEOTIA. Thebes. Circa 480-460 BC. Hemiobol (Silver, 6.5 mm, 0.54 g). Half of a Boeotian shield. Rev. ⨂ in an incuse square. BCD Boiotia 356a (this coin). HGC 4, 1362. A rare variety. Clear and toned. Obverse possibly double-struck, otherwise, good very fine.
From the "Collection sans Pareille" of Ancient Greek Fractions and from the BCD Collection, Triton IX, 10 January 2006, 356b.

Do note that the reverse type is a theta and not a wheel!