This pillar is built around struck and sustained tones: singing bowls, gongs, crystal chalices, tanpura drones. The tuning is often 432 Hz, but the tuning matters less than the decay.
A bowl strike is a fundamental sine plus inharmonic partials at roughly 2.75x and 5.4x, each decaying at a different rate. That is why a bowl sounds like one event and then a long tail rather than a chord. Gong seeds stretch the tail further and drop the fundamental.
Drone seeds use three detuned sawtooth voices through a lowpass filter. The detune is small, so the voices beat against each other slowly. That beating is the texture; there is no melody to follow.
Use these for seated practice or a short reset between tasks. The natural spacing of strikes sets a pace, so you do not need a separate timer to keep you honest.