Son of King Sudasa, originally his name was Saudasa. He was married with Madayanti.
At the request of Kalmashapada, sage Vasishtha fathered a child with her. The pregnancy lasted twelve years, Madayanti hit her body with a stone and Asmaka, stone, was born. Madayanti died.
Read about Kalmashapada here
http://www.sushmajee.com/biographies/bio-Sa-1/saudaas.htm
For a story visit
http://innertraditions.blogspot.com/2009/10/madayanti-woman-who-tore-open-her-womb.html