This is the pictograph of a mountain range set at an angle. It is the noun mountainside.
Illustrative Text Reference:
Kalibangan: Seal: K-18 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 302: Collections in India: Suomalainen Tiedeakatemia.
Comment:
This is Mahadevan's sign number 1186, which I have redrawn to reduce the angle of the slope..
Image Credit:
Mountainside: Lynn Fawcett, 2017.