Diatoms are also called 'Pearls of Ocean'. Why? What is diatomaceous earth?

(N/A) $1$. Diatoms possess a shining,silicified,two-valved cell wall known as a frustule. Due to this unique,glass-like appearance,they are often referred to as the 'Pearls of Ocean'.
$2$. Diatomaceous earth: It is the accumulation of the siliceous cell walls (skeletons) of diatoms that have deposited over billions of years in their habitats. Because these cell walls are composed of silica,they are resistant to decay.
$3$. Diatomaceous earth is gritty in nature,which makes it highly useful for polishing,filtration of oils,syrups,and in various industrial applications.