Comment by ASalazarMX

I knew those as otoliths, and the vertigo they cause is so intense and annoying I never forgot the name: benign paroxysmal positional vertigo

Fortunately, the Epley maneuver is very effective, if done correctly. Unfortunately, if done incorrectly it can worsen the symptoms. It's all about identifying in which semicircular canal are the otoliths before moving them.