Gastropod and possible bone Irish beach find

[Colboy]

Hello - I'm new here and would appreciate any insight members of the group can share on the two fossils my daughter found on our beach walk today, in Dublin, Ireland. The shell is 1 inch in diameter. Thanks!

Edited March 8, 2019 by Colboy

[Fossildude19]

Welcome to the Forum.

 

Your first item is a gastropod, rather than an ammonite.

Can you put a match/flame to the bone?

If it burns, or gives off a burnt hair smell, it may be modern. 

Doesn't really look like bone to me, but other angles may change that. Bottom, front, back, sides.

Regards,

 

 

EDIT: Where in Ireland? 

I took the liberty of enlarging the and brightening the bone image. 

 

[Colboy]

@Fossildude19 thanks for replying and gastropod clarification. On the other item, answers below and additional images attached:

1. It does not burn when exposed to flame.

2. It was picked up on a beach in Howth, 10km north of Dublin city.

[Fossildude19]

I think the "bone" is actually geologic in origin. 

Looks more like rock to me, but wait for some other opinions. 

 

Here is a geologic map of Ireland. 

The area around Howth looks to be composed primarily of Silurian Bedrock. 

So the gastropod is most likely from the Silurian Period. 

That makes the snail far older than the dinosaurs, at over 400 Million years old. 

From Wikipedia:

"The Silurian is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at 443.8 million years ago (Mya), to the beginning of the Devonian Period, 419.2 Mya"

 

 

[JohnBrewer]

Could be a sponge maybe?

[Colboy]

@Fossildude19 & @JohnBrewer thanks for the thoughtful and informative replies. Nice inspiration to explore further.

[Mike from North Queensland]

To me the bone cross section looks to be parallel to be anything but a modern cut bone with the saw marks worn off.

The nodule material that is starting attaching to one end is typical of a marine (beach) environment. 

 

Mike

[Colboy]

@Mike from North Queensland hi Mike - I too thought it was likely modern butchered bone, when I first saw it, but it's definitely inorganic. I exposed to flame, it doesn't burn. It's coarse/gritty to touch. How old would be considered modern? There's evidence of Neolithic settlement in the area, c.5000 BP. Could bone petrify in 5000 years? @JohnBrewer's suggestion of sponge is also something to consider.

[Colboy]

The cross-section of a fibula looks remarkably similar. Although that seems unlikely! 

 

https://www.researchgate.net/figure/Cross-sections-of-ilium-left-and-fibula-right-from-both-sides-of-the-same-cadaver_fig2_256329465

Edited March 8, 2019 by Colboy

[ynot]

Bone piece looks like it came out of a ham steak.

I think it is modern butchered bone.

[Scylla]

5 hours ago, ynot said:

Bone piece looks like it came out of a ham steak.

I think it is modern butchered bone.

I agree. But the gastropod is a fossil. Old bones may not burn. I once pulled a modern bone out of a campfire and if I hadn't put it in myself I could have been fooled that it was a fossil. The organic portion of a bone burns (basically the fats and proteins) but the mineral portion of hydroxyapatite does not.