https://www.scientificamerican.com/article/toffee-planets-hint-at-earths-cosmic-rarity/

It might not occur to us surface dwellers very often, but rocks can flow—more like the way exceedingly lethargic toothpaste would rather than water. Exposed to the extreme temperatures and pressures that reign in the hellish realms far below our feet, rocks can practically swim—slowly diving down and bobbing up through much of Earth’s subsurface.

For some rocky worlds around other stars, what is true for Earth’s innards may extend right up to the surface. Super Earths—sometimes rocky exoplanets that are bigger than our pale blue dot but smaller than massive ice giants such as Neptune—have comparatively strong gravitational fields. Thanks to this extreme gravity, some scientists suspect, rocks on such worlds would flow far closer to the surface.