Name That Parasite...

Name This Parasite
Clue #1- We live in the ear. 
Clue #2- Humans are generally immune to us. 
Clue #3- We cause coffee ground-like discharge 

The answer: Ear Mites

Ear mites are tiny infectious organisms that can just barely be seen with the naked eye, but usually must be detected by examining a sample of ear debris under a microscope. Ear mites usually produce a dry black ear discharge that is commonly said to resemble coffee grounds.