Bone identification

November 15, 2021 4:29 PM

I found a bone (vertebrae?) washed up on the beach in Port Townsend, WA this weekend. What kind of animal is it from?

Pics are here!

posted by quiet coyote to Pets & Animals (4 answers total)

To me, it looks much more like a giant acorn barnacle shell than anything else - you can see where there was a second and third barnacle attached to its side. Here's a link with some photos for comparison. You can test if it's a seashell by putting it in a cup of vinegar & watch for bubbles; the acid will start dissolving the calcium carbonate in the shell.
posted by azuresunday at 5:44 PM on November 15, 2021 [4 favorites]

Response by poster: Oh wow, I wouldn't have guessed that! And yes, it bubbles! But just to make sure I'm understanding the test, don't bones have calcium carbonate too?
posted by quiet coyote at 6:20 PM on November 15, 2021

The primary calcium-bearing mineral in bone is hydroxyapatite, not calcium carbonate. I'm not sure but I think hydroxyapatite may be less reactive with acids than calcium carbonate.
posted by biogeo at 8:12 PM on November 15, 2021

I agree with azuresunday above, your find looks like an acorn barnacle.

I just tested a bone I found in the woods. Same amount of bubbles in vinegar and in water. I think it's trapped air escaping out of small pores in the bone. Granted, this is only one bone, and it had been sitting as decoration in my flower pot for a while....
posted by Guess What at 4:35 AM on November 16, 2021