I agree, looks like a celt. Some might question that, due to the material, but I've got celts just as grainy. I guess I might change my mind in hand, but looks like a celt with a bit blunted from use...
Looks like a celt to me, too. It may have been polished originally, but depending on the material and soil conditions, deterioration of the stone might've occurred over many years. Good find!
I'd like to think you found a a celt or an hard stone adze but the picture quality is too poor to to tell whether your stone is just a rock or an artifact.
Sure does look like a celt with a nice ground edge on the end. The overall surface of the stone does look odd, as if some salts or minerals have accumulated on it over time.