"The first young that hatch do not start digging at once but lie still until some of their nest mates are free of the egg. Each new hatchling adds to the working space, because the spherical eggs and the spaces between them make a volume greater than that of the young and the crumpled shells. The vertical displacement that will carry the turtles to the surface is the upward migration of this chamber, brought about by a witless collaboration that is really a loose sort of division of labor. Although the movements involved are only a generalized thrashing, similar to those that free the hatchling from the egg, they accomplish four different and indispensable things, depending on the position of the turtle in the mass. Turtles of the top layer scratch down the ceiling. Those around the sides undercut the walls. Those on the bottom have two roles, one mechanical and the other psychological: they trample and compact the sand that Filters down from above, and they serve as a sort of nervous system for the hatchling superorganism, stirring it out of recurrent spells of lassitude. Lying passively for a time under the weight of its fellows, one of them will suddenly burst into a spasm of squirming that triggers a new pandemic of work in the mass. Thus, by fits and starts, the ceiling falls, the floor rises, and the roomful of collaborating hatchlings is carried toward the surface."