The Indus Dictionary Project
This is a pictograph of a horn. The number of segments indicates the size of the horn, which is two Indus units. The size is determined by the type of horn. The type of horn would in turn, suggest the usage and value.
Mohenjo-daro: Seal: M-331 a: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 84: Collections in India: Suomalainen Tiedeakatemia.
Mahadevan may have assumed that M-331 was a tablet rather than a seal. The orientation of sign number 1090 therefore differs from that in Joshi and Parpola.
Inscription M-331 tells us that this horn was a musical instrument, which was used to announce someone's arrival.
Indus Script Sign Number 1090 (mirrored): List of Sign Variants: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.