Each known element be broken down into any simpler substances. fill in the blank

Elements can be described using atoms.  Each element has an atom that corresponds to it and since atoms are made up of even smaller particles you can break up elements in to simpler things.  It is just that the simpler things have no real chemical identity and can't be used. (atoms (and therefore elements) can be broken up into protons, neutrons, and electrons).

I hope this helps.  Let me know if anything is unclear.

cannot be broken because elements are made of atoms an atoms nither be created nor be destroyed.

Herbivores, carnivores, omnivores, decomposers, herbivores