Hey I detect on beaches so to my belief that’s is a dirty caked piece of jewelry necklace or bracelet . That’s what happens to non gold or silver over time called corrosion u should clean look for a stamp if u can see that it’s hand made possibly old or colonial be gentle no chemicals
1970 COMPASS-
WHITES SILVER EAGLE-
WHITES DFX, 4X6DD COIL, 6X8DD COIL, 950 COIL, 10X12SEF COIL-
GARRETT PRO POINTER AT, GARRETT AT PRO , MINELAB EXPLORER SE with 8.5x12.5 Cors coil
Nokta FoRs Gold, a Gold Cube, 2 Keene Sluices and Lord only knows how many pans....not to mention a load of other gear my wife still doesn't know about!