Some decades ago I was travelling around Australia and was lucky enough to climb Uluru. Pools on top of the rock had been produced by recent rain and, curiously, in many of them strange aquatic invertebrates were present (see photo).

This specimen is sitting in my camera lens cap, which has a diameter of 62 millimetres. It looks like an ancient trilobite. Why and how was it on top of the famous, massive rock, and what is it? What happens to the creatures when the short-lived puddles dry up?

Gavin Chester, Dwellingup, Western Australia