Oyster Looking rock

[Shimmeron]

The person who owned my home before me left quite a rock collection around my yard. I seriously thought this was a cow patty when I first saw it. But upon closer examination it was just a weird, oyster shaped rock in a grey limestone like clay. It has shell casings around a few of the ridges and seems to have an oyster like shape. It also has small clear crystals that crust some of the ridges and crystalline matter mixed into the grey sludge clay its encased in. It weighs a lot, so I didn't think this was a fossil, but a friend who has more experience with fossils thinks its a fossil. I might upload some better pics later after I charge my camera.

[Innocentx]

Better pics would definitely help. There may be edges of shell material here but hard to tell.

[Miocene_Mason]

If this is from the same place as the other one, Mississippian is the most likely age. Better pictures definitely needed.

[Shimmeron]

Edited July 4, 2018 by Shimmeron
Here are the additional pictures of this rock, fossil or ?

[Shimmeron]

I think the lighting was better with the last two pictures and more of the details showed up with the angles. I have no clue what this is, but the scientist in me wants to crack this thing open like an oyster and examine its insides. I'm an environmental scientist, not a paleontologist or geologist, so its hard to hold back. 

Edited July 4, 2018 by Shimmeron

[Innocentx]

10 hours ago, Shimmeron said:

the scientist in me wants to crack this thing open like an oyster and examine its insides

I would say go for it. I'm not seeing anything an the outside.