Mathematical curiosities are fascinating concepts or numbers that often have unique properties or surprising relationships. For example, the number 0 is the only integer that is neither positive nor negative, while pi is an irrational number that represents the ratio of a circle's circumference to its diameter, extending infinitely without repeating. Another intriguing curiosity is Fibonacci numbers, a sequence where each number is the sum of the two preceding ones, starting from 0 and 1. This sequence appears in various natural phenomena, such as the arrangement of leaves on a stem or the pattern of seeds in a sunflower, showcasing the connection between mathematics and nature.