Maybe just a rock, but wanted to get anyones expertise on this. A friend of mine found this on the river near a ford a few years ago. If anyone is familiar with the Wabash in Indiana, there was significant native american activity. Again, it may be just a "rock"!
This is just a SWAG, because I really don't know what you have there. But I have made a few reproduction stone age arrows, and shafts don't come off a plant straight, and they don't stay straight, and they don't fly accurately bent. So shafts have to be straightened. They can be straightened by heating over coals and using your thumbs to counter bend it. But there are times that the thumbs just aren't enough, and the shaft needs to be bent a little more, or for what ever reason you need to have a little more force. That stone could have been set in a fire and heated, and the shaft placed in a groove and bent to straighten it. There isn't anyway to tell if that's what they really did with it, but I don't think those grooves got there naturally. Another option besides straightening shafts is smoothing. Sand in the groove and rub the shaft back and fourth. Here is a photo of some of the arrows I, or friends of mine have made. They have reproduction points, the shafts are rose, or red osier dogwood, or willow, or ocean spray, or cottonwood. I don't remember now which arrow is which, and all those woods have been used. One made by a friend has a shaft made with pragmitie reed and a footing for the point made from a short bit of bitter brush, very much like the Indians of eastern Oregon's high dessert would have made it. The paint is pigment and hide glue, the feathers are turkey or goose. The point and feathers are attached with hide glue and and tied on using sinew remove off the back strap of a deer. So I'm speaking from problem solving when attempting to make and arrow, the entire idea was to make the bow and arrows, and hunt and harvest a deer with it. I never got a clean kill of a deer, but I did hit one that I finished off with a modern arrow. But that's a different story.
Not sure what it is but it don't look natural to me. Try posting it on the Indian relic forum, maybe somebody will know what it is. I like it! Tennessee digger