The actual calf and the made object differ in decisive respects: one is a living animal, the other a fashioned artifact. Yet metaphor does not require total identity across all attributes. A particular salient jāmiʿ can justify the transfer.
The object's calf-like configuration makes the borrowed animal-name intelligible without implying that the object literally belongs to the living species.
Metaphorical identification claims an assimilation in one relevant respect, not a complete equivalence of natural kinds.