Cretaceous Period, 145-65 million years B.P. A group of five natural iridescent rainbow shell Cleoniceras besairiei ammonites; held in a white card collector's tray. 30-39 grams, 45-52 mm width (182 grams total, 78 x 100 mm including tray) (1 3/4-2 in. (3 x 4 in.)). From Madagascar. Acquired 1950s-1960s. Bristol paleontological collection. [5, No Reserve]