Dead ends of evolution

Ammonites are not always round: twice in the course of millions of years there were attempts to build a angular shell: in Morocco there are actually tiny ammonites that tried to build a rectangular shell 335 million years ago. And in China, around 10 million years later, even triangular ammonites appear! However, these soon return to their “normal” shape as they grow larger.

Neither experiment seems to have brought any great advantage to the animals and are not repeated in the course of the Earth’s history.