Not trying to be a smart alec, but just what do you see on that stone that makes you believe it's an Axe? It has no Blade on it. Shows no evidence of pecking or grinding or ever being altered by man. Has no groove for hafting, etc.
These are actual Stone Tools.
But, definitely this piece is questionable and if I give it more consideration probably natural.
On the west coast you have to have an open mind.
Fred Flintstone and minecraft did not add to the NA tool kit. Fitting in your hand means (truly) nothing. If this was pecked to fit and strike it would not be in question and it would not be so crude, if the time was taken to rough it out, very little effort would have remained to finish it and this rock is in no way "finished". As an axe it has no bit, as a pestle it has no use.