Small life

Vinson Brown, The Amateur Naturalist Handbook, Boston, Little, Brown and Company, 1948, p. 279-280.

Wolflike water beetles dive at the armor-cased caddis-worms, who have surrounded themselves with a protective shell sticks or stones cemented together with silk. Every bit of sheltered hideaway is occupied by some form of life. Flatworms ooze
along the undersides of rocks; snails crawl up the water plants; and even the mud of the bottom is filled with small life.