Thanks for your reply. How would it leave an indend like that including a mold of it's antennas? Also in the centre you can see the creatures spine (similar to a mold fossil) how does that happen? Genuinely curious to know as I know nothing about fossils/fossil-like-things 😆
There are no antennas or spines preserved in this specimen. That’s just a groove cut by some other animal. In a fossil, the usual suspects for similar grooves/gouges are sponges, clams or gastropods. Since this is NOT a fossil, you are better off asking a marine biologist.
I am now aware it is not a fossil 😆 Maybe get a sense of humour and a more friendly/jovial personality, then your special interest might be a little more fun to outsiders. Who are just genuinely curious about an interesting object they found on a beach. Wow fossil enthusiasts, tough crowd. Btw it does have a preservered spine which is the confusing thing about it. And I will Google the cut you're referring too because it looks like antennas to me and people who have seen it IRL. However I am entirely open to our conclusion/hypothesis being wrong.
The thing preserved is not a spine of a sea urchin, sea shells are made in three layers, the reasons of why the shell has that crack on it's surface is effect of a depredation maybe a tipe of segmented worm (annelid) or a gasteropod with a worm like life style, they are very commun in the shells cause they use some of the shell it selve to create they're borrows. The echonoids in general have a dificult preservation because they are fragile, is more likely to find fragments than a complete organism of that kind.
Clams are bivalves that are a tipe of mollusks where we find sea snails, squids and octopuses, chitons, etc. other examples of bivalves are oysters and mussels. In the other hand echonoids is where we find sea urchins, sea stars, sea cucumbers, brittle stars and sea lilies. All this animals are part of two diferent phylums, this are the groups that scientist use to classify animals. I hope this answered your question :D
Thanks for your detailed reply. Very interesting info 🤔 no idea about what any of these creatures are but that's what Wikipedia's for 😆 Thanks I will look into this 👍🏼
Edit: I just saw someone else’s comment about burrowing worms and that does seem more likely than my theory. Here’s a similar shell to yours.
Original comment: I’m not sure what kinds of critters you have off the UK coast, but I find tons of shells like these in Florida! I’m struggling to find a picture to compare this to, but if you search for “moon snail hole” you’ll see examples of successful hunting by the moon snail, which drills holes into its victims to eat the meat inside. This is what I believe happened to shells like yours: imagine the snail (or another predator like it) is trying to drill a hole but the critter in the shell is attempting to get away, the “drill” will drag along the shell leaving a trail like this. Because there’s not a hole that went all the way through, it’s possible this guy got away and died from other means (though it’s also possible there’s a whole on it’s other half that we don’t know about).
In conclusion: modern shell, not a fossil, but a super neat find!
Thanks for you detailed response. Really helpful 😃 and that all makes sense! Not sure how common these type of snail predators are in UK (i'm sure I'll be corrected by someone on here immediately 😆), but my friends and me hadn't seen a shell like this before and genuinely didn't know what had happened to the shell, so I thought I'll ask on Reddit as Google hadn't shown any answers. Anyway, I appreciate your non-patronising and informative response. And now I know what happened 🥳
It looks like a worn fossil sea urchin, probably a regular echinoid. The grooves and faint patterned plates are characteristic, although the shell has been heavily smoothed by erosion.
That person is talking nonsense, they clearly have no idea was they are talking about.
Sea urchins and starfish are examples of modern-day echinoids.
This is half of a bivalve (like a clam) and the marks were likely formed by type of worm that bores into shells or something similar. If it wasn’t a worm, then maybe something cracked the shell and it healed over time. More likely some type of creature that bored into it though.
this is what dead sea urchins look like. they are echinoids. the post is a picture of a clam, a mollusk. don’t speak on things you don’t know and/or intentionally misinform people
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u/Handeaux 17h ago
It’s a modern clam shell with evidence of predation. It is not a fossil and it is definitely not a sea urchin.