re: Can you explain the process, Nick?
Well, you can imagine Marvi's picture, covered with dust.
The way it works is that thermal contraction splits off the outer shell of the rock.
On Earth, this is enhanced by chemical weathering, weakening the outer crust, and by freeze-thaw action which is particularly good at forcing things apart when water freezes.
Onion-skin weathering is found in many environments from arid deserts to cold temperate climates.
Perhaps this rock had a particularly susceptible structure or chemistry?