Large bow shaped agate bead. A very similar bead may be seen in Lankton's "A Bead Timeline". Lankton says that a bead very similar to this, and the one in his book, was excavated in a 3rd century BC Sarmatian grave. The bead is intact but has been capped with 22K gold granulated caps. Minor surface wear and one fine crack(see first photo)  The bead is entirely solid.

50mm x 14.5mm