You can see the ridges running in various directions across the rock (the thicker, overlapping wormy-looking things are actually sand dunes, blown by the wind into lower-lying regions).
Elsewhere, across eleven galleries, we see much that is characteristic and familiar: highly polished mirrored surfaces which play tricks with our seeing; writhing, wormy extrudings of cement.
He's thinking about moths and butterflies, and how they radically change shape as they grow, from little wormy, caterpillar critters to airborne beauties.