After their metal detector indicated a metal object they found a nail .
They kept digging when the metal detector continued to register more metal objects , and they found several sherds of pottery , and then some coins , about 50 cm beneath the surface .
After their metal detector indicated a metal object they found a nail , but they kept digging when the metal detector continued to register more metal objects , and they found several sherds of pottery , and then some coins , about 50 cm beneath the surface .