Simplify the following text for a Grade 9 native English-speaking person.
Original: Navel lint ( also known by names such as navel fluff , belly button lint , pupik lint , and belly button fluff ) is an accumulation of fluffy fibers in one 's navel .
Simplified: Navel lint , also called belly button lint , belly button fluff or navel fluff , is an collection of fluffy fibers in one 's navel .