I have this posted on the bone section, but it was suggested I post it here as it may be a shell instead of a bone...any ideas? Thanks in advance!
I found this on a rocky salt water beach in the Pacific Northwest in the USA. It looks like a spongy bone to me, but maybe not! Any ideas? The flat spot on the first picture is very purple. Any help with identification would be very much appreciated!
It's a piece of shell which has been bored into by another organism. The holes look very similar to one I found some time ago. See this thread: http://www.nhm.ac.uk/natureplus/message/15636#15636
Thanks Drosophila...it definitely looks like it's been the victim of boring sponges! Now, my next question is what kind of "shell" this is...it is a puzzle to me, I've never seen a bivalve of that shape and size locally.
So, thank you again, whatever it is, it does look like it's been had by the sponges!
I'm no expert on shells, but doubt if even an expert would be sure as it's only a piece, and pretty well chewed! (Could a sponge be described as chewing anything - they don't have teeth!!??) Unless someone could guess from the shape shown in the first pic. that could perhaps be part of the hinge muscle attachment area if it's a bivalve, I would think it is a bivalve as it seems too flat for anything else - maybe the top part (furthest from the opening) of a clam?
In other words, your guess is probably as good as mine
Correction! I think it may be a univalve mollusc. I was at someone's house this afternoon and they had some tropical shells. I looked inside one like a kind of large whelk or conch, and it had a groove at the entrance that looked very like your find.
This pic is of a Murex shell from Florida. On the left hand side is a grooved area froming a "tail" that could be the same kind of thing as the grooved area in yours. It seems they are different lengths and shapes depending on species.
Mike on the bone board suggested a brachiapod...and so I looked at pictures of some brachiapod brachidium, which is a coiled tube that looks a lot like the channel in my object. I don't know the etiquette of posting pictures or links here that are not mine, or I would post one. I had thought of conchs also, so that perhaps could be the case although they are not native to my area.
Thanks for your help!
Well done for the research. I do see curved marks in your specimen's 'channel', but they are not related to the spirals described as part of some brachidia. Brachidial coils really are coils (sometimes just a loop). A brachiopod's valves articulate at a hinge, which comprises mechanically male and female parts that interlock somewhat; muscles and other tissues prevent the valves falling apart. We (John and I) are seeing in your 'channel', one half of some of that interlocking geometry.
But we still have the issue of size.
'The largest modern brachiopod is about 10 cm (4 inches) in length.'
Even a giant fossil one would be only about a foot across, and in that your specimen might just about be the right size. But yours is not a fossil.
Modern large bivalve maybe, along the lines of a big clam, perhaps.
Still a puzzle...
Are these holes actual holes, or are they rather bubbles? Though they do look dark, (suggesting holes), they're very evenly distributed. If bubbles that'd suggest an industrial origin.
Identified! Thanks to all who have led me to the answer. I finally (brazenly) contacted our local natural history museum, and they were kind enough to reply with the following information (very much shortened!) It turns out this is indeed a bivalve, commonly named "Giant Rock Scallop", or Crassadoma gigantea. They do get as large as 228 mm and are localized to the Western United States coast, normally found in deep water. They are a favorite of the boring sponge Cliona as their shells are so thick. The purple is indeed part of the hinge plate, and the groove is for the ligament that opens and closes the scallop. This information can be found in a book "Bivalve Seashells of Western North America" published in 2000 by the Santa Barbara Museum of Natural History, pages 236-238. I can't thank everyone enough, this has been fascinating.
Well done you for the extra and fruitful sleuthing.
Here's a photo of Crassadoma gigantea, showing the groove and purple colouration (top middle), so we can all see the part your specimen comes from -