This is a pictograph of an adze.
Illustrative Text Reference:
Mohenjo-daro: Tablet in bas-relief: M-483 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 116: Collections in India: Suomalainen Tiedeakatemia.
Comment:
In inscription M-483, the adze has a different orientation (shown right).
Image Credits:
Indus Script Sign Number 129: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.
Rotated Version of Mahadevan's Sign Number 129: Lynn Fawcett, 2018.