Take for instance the pyramidal ammonia (NH) molecule.

What is the hard sphere diameter of ammonia molecule?

The ammonia molecule had already been proposed as such but Essen was convinced that caesium would prove more stable.

Nitrogen-13 is used to tag ammonia molecules for PET myocardial perfusion imaging.

A member of the amino group, it may be regarded as an ammonia molecule which has had one of its hydrogen atoms removed.

Hydrazine can arise via coupling a pair of ammonia molecules by removal of one hydrogen per molecule.

If the pH is low, the equilibrium shifts to the right: more ammonia molecules are converted into ammonium ions.

The ammonia molecule readily undergoes nitrogen inversion at room temperature; a useful analogy is an umbrella turning itself inside out in a strong wind.

I do not see the pyramid in the ammonia molecule.

It was based on the absorption line in the ammonia molecule, but most are now based on the spin property of the cesium atom.