They do not like heat. Even thumb crassula tom regarded as a common crassula, that does not prevent it thumb crassula tom being one of the most exquisite. Crassula Devils Horns start out green and turn red when exposed to the sun and the elements. Crassula 'Buddah's Temple forms stems of stacked triangular leaves of velvety grayish-green in a beautiful Oriental "pagoda" shape.