The average sperm cell swims at 8 inches per hour.
76
Your thumb is about the same size as your nose.
124
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The average person's skin weighs twice as much as their brain.
131
Enamel is hardest substance in the human body.
61
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The largest cell in the human body is the female egg and the smallest is the male sperm.
682