Diatom
They are one of two great groups of single-celled organisms in the sea. The other is the coccoliths. Since diatoms are made of silica, and coccoliths are made of calcium carbonate, they do not grow in the same places in the sea. This was first discovered by T.H. Huxley in his voyage on HMS Rattlesnake, 18461850. Diatoms are also found in some soils and in some waterways on land.