Ancient Throwing Stone or Tool? greyhound plate and then (I think) feet

and then (I think) feet of sorts carved at bottom

Resignation

These will be packed SUPER carefully for safe travel

The paper size is just shy of that

13 1/4" x 9 3/8" x 3 1/8"

Ancient Throwing Stone or Tool? greyhound plate and then (I think) feetI purchased this from a wonderful dealer in New Hampshire whose cabinet of curiosities includes objects decommissioned from museums and science departments as well as gathered from estate collections all over. She didn't know the origins of this stone and neither do I, but it sure looks like a throwing stone to me! If not certainly used as a tool of some sort, with a couple of divets on the bottom one just the right shape for a thumb gripping it.