This shell is an ammonite, a marine animal that became extinct about 65 million years ago. Just around the same time the dinosaurs disappeared. The shell's unusual colouration is found only in ammonites from Alberta, Canada and is a result of millions of years of high temperatures and pressures which account for the iridescent effect.
I did not make this up; it is taken verbatim from the plaque at the Museum of Natural History. I really enjoy visiting museums because the very concept of 65 million years makes me feel very happy and very sad at the same time.
We were also lucky to see a live display of snakes and lizards. I am not a reptile lover but there were some very interesting specimens. According to the map this boa is native to Trinidad and Tobago but I can't say that I have ever come across it. He was, like me, a long way from home.
I was also able to see a green mamba. Green mambas have assumed mythic proportions in my mind. There is that awful scene in Barbara Kingsolver's novel "The Poisonwood Bible" where the green mamba strikes and kills the child.
But this green mamba was surprisingly innocuous looking. It lacked the menace of the vipers and the garish-ness of the coral snake and other poisonous creatures that alert us with their vibrant, too-bright hues.
The mamba was innocent looking. Gentle almost. If I had to cast the part of the snake in the Garden of Eden, my vote would go to the green mamba.