Lovely obverse die
LUCANIA. Thourioi. Circa 443-400 BC. Nomos or Didrachm (Silver, 21 mm, 7.69 g, 3 h). Head of Athena to right, her helmet adorned with an olive wreath: B above visor. Rev. ΘΟΥΡΙΩΝ Bull butting left; in exergue, fish to left. Gulbenkian 85 (same obverse die). HN III 1758. Attractive toning with soft blue and golden hues; well centered and nicely struck from a lovely obverse die. Minor surface porosity, otherwise, very fine.
The Gulbenkian catalogue notes that of the issues with die-letters, which includes nearly all the letters of the Greek alphabet, those with the letter B as here are by far the rarest.