Found this odd rock the other day...

[Savakuda]

I live in Northern Wisconsin in an apartment complex, and the pathways outside are decorated with various rocks. I found this among them, and the closest thing I can think of is that this is a femoral head that is very encrusted in crystal. I'm not an expert, and I've only found one real fossil in my life; I'm also not sure where else to show this to possibly get some information, so any guesses would help out a bit.

There is some black crystal inside of it, so I'm also wondering if this might just be some odd geode, but the shape just has me baffled.
There is also some sort of pattern near the white portion that looks brown and has a sort of line pattern going up/down from that white portion.

Thank you to whoever can shed some light here.

[Fossildude19]

Rock gets my vote on this.

 

@Harry Pristis  @jpc

[Savakuda]

I'm going to have to crack it open and see what it looks like inside probably. I've had other people say the same thing.

Thank you for your input.

[jpc]

Hi Savakuda-

I say this as aguy who has collected and prepared many many fossil bones... there is not bone texture or genuine bone shape here.... Just a rock.   : (

 

[Savakuda]

Thank you. I've been told that too lol.

[jfokeefe]

Hello, it looks similar to some of the rocks near me. It won’t be different inside and it’s not bone. It might be a steinkern which is an inner mold of a fossilized bivalve or brachiopod or can be of other species as well. I’m finding the rocks on all the rock piles I can see a design on them in the shape of five sides with a star inside them l, that’s what I see on most of them. If it’s limestone or dolomite which I think that’s what that is it’s a raised design and on harder chert and some other rock you can see that same design or pattern inside the rock in the colors, if this makes any since to you.