Data:

Here are some pictures of a fossil from our farm in Kansas that I have not been able to identify. The farm has a shale bed which has produced shark's teeth, vertebrae, and tons of other identifiable fossils. This one is a mystery.

Thanks for your help.

Email 2: Hey Avril,

I think we need to add some additional information about this "rock". It is definitely not made up of any limestone. We made fence posts out of limestone all over that farm and I know what it looks and feels like. Also, the "fins" are ALL made of two, flat quartz like looking plates, fused together, thru out the sphere. The rock portion or "fill" looks more like rough concrete, and my weight lifting sons guestimate it to weigh around 300 lbs.

Send Ideas to: Mike

Identified:

Discussions:

• The Kansas sphere is a ‘septarian nodule’. These concretions form in the shale, often around a rotting organism that was quickly buried. The rotting forms a change in the local water chemistry, precipitating calcite (or siderite) in the mud around the material. At a later time the concretion split open in different directions and these were filled with calcite crystals. There may be a recognizable fossil in the concretion, but the secondary cracks would mess it up. Similar ones in Utah are sometimes cut and polished as decorative stone. ... Allen A.

• The thing from Kansas isn't a fossil. It's actually an example of differential erosion: a long time ago, this rock had fractures. These fractures were filled up by a mineral that is more resistant to erosion than the surrounding rock. The rock weathers away faster than the mineral, creating these projecting "blades".
  If I had to guess, I'd say the rock is limestone, and the "blades" are calcite.
  Cheers, James C.