I made some exchanges with a friend in Hungary this summer who wanted fossil shark teeth. Below are a pics of the gastropod Pyrgulifera sp. from the Santonian stage of the Cretaceous. They were collected from old coal mines near Ajka-Csinger, Hungary. The preservation is really nice and I especially like the specimen preserved with matrix.
This specimen is loose from matrix and has some nice blue color on it. I'm not sure if the color is the result of minerals in the sediments or they are remnants of the original shell colors.