Radiolarians are exquisitely beautiful amoeboid protozoa that have been living as zooplankton in the world’s oceans for about 600 million years.

These tiny, siliceous, single-celled organisms with their intricate mineral skeletons make-up the world's smallest clocks. Because they occur in continuous and well-dated sequences of rock over large portions of the ocean's bottom, these minuscule microfossils act like a yardstick, helping geologists accurately date rock from around the globe from the Cabrian onwards.

A great temple to the god Amon was built at Karnak in Upper Egypt around c. 1785. It is from Amon that we get his cephalopod namesake, the ammonites and also the name origin for the compound ammonia or NH₃.