The external coverings of diatoms are made up of , while slime molds have cell walls containing . diatoms are because they make food through photosynthesis, while slime molds are because they eat decaying plant matter.

The external coverings of diatoms are made up of frustule which contains chloroplasts. Chloroplast is a organelle that has chlorophyll  pigment that captures light energy from the sun and utilize it for photosynthesis. Slime molds comes under category of fungi. Their cell wall is made up of cellulose. They undergo spore formation, their spore sac get rupture as cellulosic layer is light and releases spores which settles on the decaying plant matter.

all matter is made up of atoms

in any element all atoms are the same

elements in a compound are always in a constant ratio: apex