Read the following statements w.r.t. diatoms: (i) In diatoms, the cell walls from two thin overlapping shells which fit together as in a soap box (ii) The walls are embedded with silica and thus the walls are indestructible (iii) The fossilized diatoms are called diatomaceous earth (iv) Diatoms are not the main producers in the oceans (v) Diatomaceous earth is used in polishing, filtration of oil and syrups How many of the above statements is/are correct?

In diatoms the cell walls form two thin overlapping shells, which fit together as in a soap box. The walls are embedded with silica and thus the walls are indestructible. Thus, diatoms have left behind large amount of cell wall deposits in their habitat; this accumulation over billions of years is referred to as ‘diatomaceous earth’. Being gritty this soil is used in polishing, filtration of oils and syrups. Diatoms are the chief ‘producers’ in the oceans.