Troezen, Argolis, AR Pentobol, ca 450-425 BC, 3.22 g. 

Archaic head of Athena facing. 
TRO, upright trident within incuse square. 

Traité III, 690; SNG Cop 156; Imhoof MG 132 and 134.

Very rare.

With permission of Numismatica Ars Classica, auction 92 Part 1, Lot 179, May 2016