While researching what caused the current invertebrate fossil of the month to have such a wonderful iridescence (www.thefossilforum.com), I came across some interesting info on preservation of color patterns in fossil shells. In Northern California where I live, most of the color of a fossil shell disappears after a few thousand years. The pattern of color is gone in a couple million years. While in Texas, I collected Texigryphea from the early Cretaceous that still had color patterns of dark ra