Shaivism
Several Lingams of Shiva in the Hindu temple Garbhagriha have been held sacred as naturally occurring mounds or rocks. Mahakaleshwar Jyotirlinga, the Jyotirlinga at Ujjain, and Madhya Pradesh are believed to be such Swayambhu.
Lord Ganesha appears as a Swayambhu (locals call it: Suyambu) in the "Poyyamozhi" vinayagar temple in Theevanur (15 km from the Tindivanam-Thiruvannamalai route), a village in Tamil Nadu, India.
Read more about this topic: Swayambhu