Labial concealment

The mechanic

A meem carrying sukun followed by ب: the lips touch only lightly, without pressing, while the nasal sound is held. In the KFGQPC text this meem is written bare, with no sukun on it.

Where it occurs

The letter that triggers it

ب

A place in the text

تَرۡمِيهِم بِحِجَارَةٖ مِّن سِجِّيلٖ

The marked spot was located in this ayah's own text at build time — Al-Fil 105:4.