Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Energy enters ecosystems in the form of sunlight or chemical compounds. 
Sentence2: Energy enters ecosystems in the form of photons.
Energy

Sentence1: a magnet moving in a coil of copper wire can cause an electric current. 
Sentence2: An electric current forms when a magnet is run through an induction coil.
current

Sentence1: Cancer is an uncontrolled cell division. 
Sentence2: Cancer often causes growth.

Cancer