Anthony D. Bianca, age 8, of Staten Island, New York, for his question:

How does an earthworm die his burrow?

Even if the earthworm had a shovel, he has no hands to use it. He has no paws or claws to scoop out a burrow or a hole in the ground. Yet every earthworm makes a burrow for himself. In fact, he burrows and tunnels through the soil day and night. This seems impossible, but he does it all by himself. Mr. Pinky happens to be an eager eater a very very eager eater. He even eats the crumby soil. He noses his way through the ground by eating the dirt and pushing his wormy body forward to fill the hollow. He digs his burrow by eating his way through the soil.

The dirt itself is not his food. But soil is mixed with fragments of rotting leave, with tiny bacteria and all sorts of other scraps of decay. These scraps are Mr. Pinky's groceries. When he fills his tummy with soil, his insides separate the plain dirt from the morsels of food. His stomach digests the scraps of food. The useless dirt is pushed down to his tail end. When he comes up to the surface, the waste dirt he has eaten is cast outside in a curly little pile. This worm casting is the dirt that Mr. Pinky took out as he built his burrow.