Help identifying possible fossil/bone/artifact

[RAC65]

I found this sticking out of the dirt on a hiking trail in southern California, Palos Verdes area. It was on a hill where there are a lot of rocks and I have found some other fossils in the general area (mostly just small plant fossils and a couple of tiny fish fossils). I am trying to figure out what it is. The top is domed, like a half cynlinder, and it has a hole in the middle. The length is about 3 inches. The hole is exactly 1 cm and perfectly round. There is a lighter color to the outside compared with the core (see photo that shows in interior edges of the hole) leading me to think it might be a fossilized bone. One end has a scoop in it that looks like another hole, but is very shallow. The bottom looks more like a regular rock. I read that one way to identify a fossil compared to a rock is to touch your tongue to it. It sticks to the tongue, as would be expected from a fossil. I am thinking it might be a branch with an insect burrow hole in it, or a bone which had a hole carved into it. The hole goes about half an inch in and then stops.

[DPS Ammonite]

It slightly looks like a worked artifact. The problem is why use such a soft rock. It is more likely a rock that was drilled by boring clams. The Palos Verdes Peninsula was underwater recently and has  13 marine terraces.

 

https://www.geocaching.com/geocache/GC19A3Y_palos-verdes-hills-marine-terraces?guid=04323ef4-d822-4ee1-bafa-533edffa90fd

[RAC65]

1 hour ago, DPS Ammonite said:

It slightly looks like a worked artifact. The problem is why use such a soft rock. It is more likely a rock that was drilled by boring clams. The Palos Verdes Peninsula was underwater recently and has  13 marine terraces.

 

https://www.geocaching.com/geocache/GC19A3Y_palos-verdes-hills-marine-terraces?guid=04323ef4-d822-4ee1-bafa-533edffa90fd

Yes, it does look like that. Down by the water, I have found many rocks with holes in them from those clams. They are always hard, dark colored rocks. This is the first time I have seen such a hole in soft material, and the first time I've seen one this high up (about 600 feet above sea level) so maybe a clam from long ago...