A microscopic photograph of a neuron. Filamentous actin and microtubules (structural proteins) in mouse fibroblasts (cells) Fluorescence. / Torsten Wittmann, The Scripps Research Institute. Courtesy of Nikon Small World.
Vestibular hair cells of the Inner ear help divers (like the one in today's pic) know their up down orientation in water. Sounds under water are magnified. When we hear sounds (whether under water or above) microscopic hairs in our inner ears vibrate.