The tutor mentions a few points about diatoms.
In my Feb 4 post I introduced protists, which constitute a kingdom of eukaryotic, mainly single-celled organisms. Protists are divided into plantlike and animal-like ones.
Diatoms, from phylum Chrysophyta, are among the golden brown algae. They are plantlike protists, perhaps the most numerous of them. In the oceans, their abundance makes them a major food source at the base of the ecosystem. Furthermore, they are prominent producers of oxygen on Earth.
Diatoms have a two-valve structure, rather like the base and lid of a box. They are well known for having glass (silica) in their cell walls, which show striking patterns under a microscope.
Diatoms have been even more abundant in the past; today, those fossils constitute diatomaceous earth, which is mined for applications such as soundproofing, filtration, and scouring powders.
Mader, Sylvia S. Inquiry into Life, 9th ed. Toronto: McGraw-Hill, 2000.
Ritter, Bob et al. Biology. Scarborough: Nelson Canada, 1996.
Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.