What are these bones?
September 2, 2013 11:55 AM   Subscribe

I found these bones (or shells) on the beach, but can't figure out what they are.

There were 5 or 6 of them, in various sizes; these are just the two I got to take home. The small one here is the smallest we found, and most were about the size of the other, though there was one that was significantly larger. The beach in question was in Midcoast Maine and this was just a few days ago-- that may or may not be relevant or helpful; I've been collecting shells in that area for my whole life and this is the first time I've seen these.
posted by dizziest to Science & Nature (13 answers total) 4 users marked this as a favorite
There's no scale in the pic -- about how big are they?
posted by brainmouse at 11:57 AM on September 2, 2013

Response by poster: Oh, sorry! The bigger one is just smaller than the palm of my hand, and the smaller one is about the size of a quarter.
posted by dizziest at 12:00 PM on September 2, 2013

The big one looks quite symmetrical, while the smaller one is asymmetrical. I don't think that's just because it's a fragment, either, it has features in common with the bigger piece (like the solid triangular point section and the central ridge) that suggest it grew in that distorted form. Because of this I'm guessing these are bits (like teeth, or plates from a turtle's shell?) of a single animal that has symmetrical examples of this part near the midline of its body and left-handed or right-handed versions out toward the sides. I guess they could also be parts of something like a barnacle or other shellfish whose shell formation might be influenced by surrounding rocks and other animals in its colony, but the fact that you've never seen anything like them before and suddenly had 5 or 6 turn up in one spot makes a single animal seem more likely to me.

How did the other examples compare to the ones in the picture shape-wise? You say they were mostly sized like the larger one; were the others also symmetrical? Did symmetry seem to correlate with size in any way?
posted by contraption at 1:45 PM on September 2, 2013

Maybe a fragment of a cuttlefish bone?
posted by steinwald at 2:00 PM on September 2, 2013

Looks like coral that has been rubbed smooth in some spots to me.
posted by Dynex at 2:08 PM on September 2, 2013 [1 favorite]

No way is that a cuttlefish bone, they don't have the honeycomb internal structure shown in the picture. While that structure is reminiscent of a coral, I'm not aware of any coral that structures its colony in such a bilaterally symmetrical fashion (typically they're tree-like and asymmetrical or loosely radially symmetrical.)

Could they be hawksbill turtle scutes?
posted by contraption at 3:33 PM on September 2, 2013

Response by poster: Most of them were extremely symmetrical, but there was one larger one that weren't symmetrical, though it might have been broken and then washed smooth by the sea. All of them have a smaller flat area at one end and a central ridge. In case it's helpful, I've also taken a photograph of the other side, with a quarter for scale.

Agreed that they seem like bits from a larger animal; my family speculated that they might be some kind of spine, because they vary in size and no two were exactly the same size. Turtle scutes seem very likely!
posted by dizziest at 6:25 PM on September 2, 2013

Scapula from a seal or seal like mammal is my bet. Old and weathered and thats why the edges are scalloped. Its not a turtle scute.
posted by fshgrl at 9:33 PM on September 2, 2013 [1 favorite]

I'm sad to see my scute theory shot down (I think fshgrl knows more than I do about turtle scutes, which is pretty much limited to the fact that they're shaped like that) but I'm not so sure about scapula idea either. Wouldn't a scapula have some curvature to it? This just seems so dead-on symmetrical.
posted by contraption at 10:22 PM on September 2, 2013

These are not mammal bones. I would guess that they are some sort of fish. If you play around with this site you might be able to find something similar.
posted by wollaston at 9:30 AM on September 3, 2013

I know you are probably not in the Arctic, but that site has many examples of a variety of sea life. The first step in bone identification is to figure out what bone you are looking at. Once this is done you can figure out what species it came from.
posted by wollaston at 9:46 AM on September 3, 2013

Please do follow up if you ever figure it out, this one continues to nag at me.
posted by contraption at 8:14 AM on October 3, 2013

Response by poster: I definitely will follow up if I figure it out, though no luck so far! The arctic bone site was neat, but I couldn't find anything that seemed right.
posted by dizziest at 8:29 PM on October 6, 2013

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