This is a pictograph of one peak from a mountain range. Thus, it is an ideograph for the adjective peak.
Illustrative Text Reference:
Lothal: Seal: L-10 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 240: Collections in India: Suomalainen Tiedeakatemia.
Image Credit:
Peak: Lynn Fawcett, 2019.