A crescent shape is a symbol or emblem used to represent the lunar phase in the first quarter, or by extension a symbol representing the Moon itself.
Waxing crescent moon
Islamic crescent art in roundabout
Hierosgamos of Sun and Moon in a 16th-century alchemical manuscript
Cross over crescent on Plevna Chapel in Moscow
Shiva, also known as Mahadeva and Hara, is one of the principal deities of Hinduism. He is the Supreme Being in Shaivism, one of the major traditions within Hinduism.
Crescent
…in the northern hemisphere) in the first quarter (the "sickle moon"), or by extension a symbol representing the Moon itself. In Hindu iconography, Shiva is often shown wearing a crescent moon on his head, symbolising his control over time, as well as his attributes of both creation and destruction. It…
Statue of Shiva at Shivoham Shiva Temple, Bangalore, Karnataka
A depiction of Somaskanda with a dancing Skanda in the middle of Parvati and Shiva.
An ancient sculpture of Shiva at the Elephanta Caves, Maharashtra. 6th century CE
The Pashupati seal discovered during excavation of the Indus Valley archaeological site of Mohenjo-Daro and showing a possible representation of a "yogi" or "proto-Shiva" figure as Paśupati (Lord of the Animals" c. 2350–2000 BCE