Diatom

A single-celled alga living inside an intricate glass house/Microscopic Life

Diatoms are microscopic, single-celled algae encased in beautifully ornate cell walls (frustules) made of silica, essentially tiny glass houses. There are an estimated 100,000 species, each with a unique geometric pattern of pores, ribs, and spines etched into their silica shells. Diatoms are responsible for producing about 20% of the oxygen generated on Earth each year, more than all the world's tropical rainforests combined. When they die, their glass shells sink and accumulate on the ocean floor, forming deposits of diatomaceous earth that can be hundreds of meters thick over millions of years.