Amphibians, a class of animals able to live both on land and in the water, consist of three groups: frogs, salamanders and the wormlike animals called caecilians.

The insect starts as a wriggling, wormlike larva, then seals itself into an inert pupa that looks like a living sleeping bag, emerging as a full-grown adult.

It’s where I learned to do things like the belly roll — where you move your stomach in and out in a wormlike motion.

The brown, wormlike juveniles “are not remarkable in appearance,” says Nicholas Teets, an insect physiologist at the University of Kentucky and an author of the study.

One of the noticeable things about microbiologist Christian Rinke’s laboratory is the startlingly loud crunching noise of wormlike larvae chewing their way through polystyrene, burrowing into blocks of the plastic foam.