I don't know the scientific name for geodes like this, but we always called them "Sugar Geodes". They are sugary white inside, they look like the sugar we used to make sugar eggs with at Easter time. They are presented in many shops dyed bright colors, pink, blue, green, etc., but really they are beautiful in their natural white. This half measures about 2"in diameter, and is about 1 1/4" deep. I am happy to combine items to save on shipping should you win more than one auction.  Please email me with any questions.