Found in a river

[Jon From Texas]

I found this in the sulphur river in North East Texas.  It is covered in a thin, light grey layer layer of rock and the center is a glassy looking grey/tan material with vain like patterns and a scaley texture.  It has a smooth bottom that looks like it might have been attached to a smooth surface.  It was in the wall of the river about ten feet below ground level.  It broke when I hit it with a metal tool while I was digging.  

 

Any help with identifying this would be great.  I've had it for years and have not seen anything that looks quite like it.

[Al Dente]

It looks like a piece of a rudist.

[FranzBernhard]

I would say the same - a piece of a radiolitid rudist. The second photo is especially nice: It seems that there has grown a tube worm on the inner side of the rudist.

Franz Bernhard

[JarrodB]

Rudist

[Tidgy's Dad]

Yup, nice find! 

[JohnJ]

Durania

[abyssunder]

I agree, it looks a rudist fragment to me also.

[erose]

As johnj suggests, look up Durania. It is a fairly distinctive large rudist of the Upper Cretaceous. 

[KimTexan]

I agree with it being Durania austinensis rudist. The large shell fragments I have a very hard. These are the 2 shell fragments I have.

However I suspect some mollusks I have found, which are coated with the gray clay/shale stuff are remnants of the infill of the rudists’s cavity or chamber of the shell. The infills are covered with beautiful nacre, I assume from the inside of the chamber that eroded away. That’s the only thing I can think the tubes would be.

These are pics of the concretions with the what I think are infills of rudists cavities.

 

The next to last pic is in the concretion with the tubes. It looks an aweful lot like my rudist shell interior.

The reason I post these with color is so that you may see what could potentially be underneath the gray layer.