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I just can't work this one out - might it be an echinoid?

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Hi Guys,

My son's friend asked me to id this and I'm embarrassed to say that I'm stumped! It's siliceous, it was found in UK and its owner has suggested it could be from Whitby (or less likely from North Cornwall or the Isle of Man). It's intriguing me because if you look through the little holes you can see daylight suggesting to me that the specimen might be fossil and not just a strange depositional feature. I'm convincing myself that I can see five-fold symmetry and that it looks like some sort of echinoid but I might be way off the mark. If you think it's depositional or diagenetic can you explain to me how you think it might have formed?


Thanks for your time.

Top view. There are holes or pairs of holes running down both sides and you can see daylight if you look through!



Side view showing horizontal holes running through the specimen. Inside of the holes appears to be crystalline silica or some grains of silica.



View of the other side, showing similar holes which go straight through



Bottom view 


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Can we get some pictures of each side with it flat on the surface? 

Your fingers are obscuring some details. ;) 

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val horn

I have been wrong many times  and am going by my own rather limited experience, but I dont see anything biological.  One reason for this feeling is that the "mineral" that makes up this piece does not look like bone or shell, nor what I expect from a fine clay or sand infilling an internal mold.

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I’m not seeing a fossil here, other than perhaps some trace fossils (burrows?) contributing to differential erosion. But there are lots of other potential explanations, I just don’t think a body fossil is one of them, at least nothing I recognize. 

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Looks purely geologic to me, but darned interesting geologic. It would end up in my " really F'ing cool box of rocks.

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Thanks so much for your input guys. The fact that the little holes are all perfectly lined up orthogonally to the layering is what's drawing me away from a purely geologic origin. It looks like it's made up of 6 layers with the identical structure to what I have described as the "bottom" of the specimen stacked up on top of each other. The indentations that criss-cross the bottom correspond exactly with where the line of holes show on the sides.






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Hi Doc Bee,

Welcome to the forum.

I see what you mean.

Maybe it is a weathered fossil, in that case an echinoid would not be my first guess though. It looks like a stack of repeated similar structures (like somites) that are typical for many groups of animals, but not so much for echinoids. Maybe a fragment of an orthocone nautiloid? Could also be just  layered mineral deposit with a fracture/weakness running through at a right angle to the layer, making it weather in that way.

Hard to tell from the remaining shape.

Best regards,


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