Every so often I visit a local retired geology professor to chat about fossils. He has a unique fireplace in his study that was mortared together with various fossils. Here are few pictures of some of the fossil embedded in the fireplace. All the images were taken with a Motorola Moto X smartphone.
I think the first image might be a model of a charophyte or some sort of
Astylospongia fossil. Next is some sort of model of a foraminifera.
The next two images are of colonial coral fossils.
Last is some sort of pelecypod fossil.