Assertion (A): Chrysophytes are found in both fresh water and marine environments and float passively in water currents.
Reason (R): Diatoms, a type of chrysophyte, have cell walls embedded with silica which makes them indestructible, contributing significantly to the formation of diatomaceous earth.

 Chrysophytes are found in both fresh water and marine waters and, being photosynthetic, they are planktonic in nature; they float freely on water. They, being photosynthetic, are the major producers in the oceanic ecosystem. 
 Diatoms, a type of chrysophyte, have cell walls embedded with silica which makes them indestructible, contributing significantly to the formation of diatomaceous earth.