What condition must a planet's interior meet to allow for effective density sorting?

Answer

The material must possess a degree of fluidity (molten or soft)

If the material is cold and solid, it resists sorting. Differentiation requires sufficient heat to melt or partially melt the interior, allowing heavy components to move through the lighter ones.

What condition must a planet's interior meet to allow for effective density sorting?
compositionlayerprocessdensityplanet