Neurons in the body need to send messages to neurons in the brain. To stay connected, some neurons have very long threads called axons. The longest neurons in the human body run from the base of your spine to your feet—they are over 3 feet long! In some cases, damaged neurons can repair themselves and their axons. This photo shows a damaged neuron from the sea slug Aplysia regenerating. The pink spikes are areas of new growth. (Image via Dylan Burnette) Read More