Opalized belemnites

Cretaceous
Coober Pedy, Australia
One of the largest formations of opalized belemnites ever offered at auction, this museum quality display specimen boasts 10 fairly complete specimens on matrix. The specimens were removed from the matrix for polishing, then reattached. Exhibiting attractive flecks of green, blue and red.
Matrix measures 17 x 11 x 9in 

Belemnites were ancient cephalopods.

From a 2006 auction conducted by Bonhams, via Bijoux et Mineraux.