How much is a real Turtle rock worth(iroquois)?

[Fred D N.Y.]

One of the places I metal detect is on an area that was occupied by a large population of native Americans. The owner of the property property found a Turtle rock carved as such. It was approx. 16" in diameter and from other sources, it is a Iroquois boundary marker. The turtle was one of the local tribes in my area in N.Y. Thanks!!!