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: Some viruses live in a dormant state inside the body. 
Sentence2: a virus can live in the brain.
viruses

Sentence1: If the skin is painful, seek medical attention. 
Sentence2: If your skin hurts, your touch receptors will sense differences.
skin

Sentence1: Zooplankton are tiny animals that feed on phytoplankton. 
Sentence2: zooplankton are microscopic.

Zooplankton