Understanding the glyph origin of 占
Divination through reading patterns from animal bones (scapulimancy) was a widespread ancient human practice. A sub-type of this, pyro-scapulimancy, in which the bones are heated/burned to induce cracks (the patterns) was practiced in Bronze Age China, commonly with turtle shells.
After preparation, the shell would have a hole bored into it and a heated rod inserted in order to crack the shell through thermal expansion. The divination would be read from the pattern of cracks, and the prognostication engraved on the shell fragments.

Source: Sources of Shang history: the oracle-bone inscriptions of Bronze Age China