Bluebulb Projects' The Measure of Things presents:
50 is about the number of Teeth in a Great White Shark's Mouth.
(Carcharodon carcharias) (average; including developing rows)
A Great White Shark has 48 exposed teeth on their upper and lower jaws. Behind these exposed teeth are developing teeth — up to 300 in about 5 rows. The sharks will continuously lose and replace the exposed teeth throughout their lives.