C. laui is the smallest species of its genus with stems that do not exceed 3 cm of width and 2 cm of height. It mostly expands horizontally to create new stems. The tones of the epidermis vary from green to brown, up to light grey. This cactus has small areoles covered with white fluff and whitish radial thorns; rarely a central white thorn. Its flowers are small and yellow with a reddish tinge on the tips. Its magnificent flowering can be admired in autumn.