The Indus Dictionary Project
This is a pictograph of a lotus bud, with the addition of some cross-hatching. Cross-hatching represents the colour of red ochre¹. Hence, Mahadevan's sign number 380 is the noun red bud or red lotus.
Chanhujo-daro: Copper object: C-40 A: Jagat Pati Joshi and Asko Parpola, 1987: Corpus of Indus Seals and Inscriptions: Volume 1: Page 338: Collections in India: Suomalainen Tiedeakatemia.
There is only one extant example of this Indus sign.
The sign is roughly half the character area in height.
Indus Inscription C-40 is a good example of the importance of context to the decipherment process. In the inscription, Mahadevan's sign number 380 is associated with lotus flower stems. Hence, we can infer that sign number 380 is a lotus bud.
Indus Script Sign Number 380: Sign List of the Indus Script: Iravatham Mahadevan, 1977: The Indus Script: Texts, Concordance and Tables: The Director General Archaeological Survey of India.
1. An explanation of why I think that cross-hatching represents the colour red can be found on the Cave Script website: https://www.cavescript.org/research/quantum-mechanics-meets-pictographs/ochre-the-substance/