This is a diatom, which is made of silicates.

As a result, after each division cycle the average size of diatom cells in the population gets smaller.

Here's an interesting one for the IT world bio silicon. This is a diatom, which is made of silicates.

Diatom cell walls are also called frustules or tests , and their two valves typically overlap one over the other like the two halves of a petri dish.

In most species, when a diatom divides to produce two daughter cells, each cell keeps one of the two halves and grows a smaller half within it.