Fossil bone?

[mr fossil]

Hi

this is what looks like a bone found in quaternary marine limestone where I only find fossil shells and marine fossils so this is definitely out of the ordinary 

I found this in Saudi Arabia Jeddah if anyone knows what this might be I would love to know 

thank you

[fossilhunter21]

It looks like a bone to me, but lets get some more opinions.

[TyrannosaurusRex]

It does not appear to have common bone like structures or textures I usually see in fossilized bones. Given the fact it’s marine in origin, I would guess it is some sort of worm or bivalve/clam burrow. 
for example, this piece from the website Jurassic James is a good example of a worm burrow.