LONDON (AP) — British officials say they have been unable to trace the rightful heirs to a trove of gold coins found stashed inside a piano and worth a "life-changing" amount of money.

The school that owns the piano and the tuner who found the gold are now in line for a windfall after a coroner investigating the find declared it treasure.

Coroner John Ellery said Thursday that despite a thorough investigation, "we simply do not know" who concealed the coins.

The hoard was discovered last year when the piano was sent for tuning in Shropshire, England. Under the keyboard were 913 gold sovereigns and half-sovereigns minted in the 19th and early 20th centuries.

The hoard has not been formally valued, but Peter Reavill of the British Museum called the trove "potentially life-changing."