annelid, annelids, earthworm, earthworms, earth worm, earth worms, earth-worm, earth-worms, worm, worms, segmented worm, segmented worms, invertebrate, invertebrates, decomposer, decomposers, decomposing, Lumbricus terrestris, worm casting, worm castings, worm-casting, worm-castings, waste casting, waste castings, waste-casting, waste-castings, soil profile, soil, dirt, tunneling, tunnel, tunnels, burrowing, burrow, burrows, crawl, crawling