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As thick as shrubbery, a tube worm colony 15 miles from the brine pool lives up to its nickname, Bush Hill. Worms stained blue a year ago show less than an inch of new, white growth. The longest, at eight feet, are more than a century old. Such communities dot the continental slope wherever free-floating larvae settled at a seep. The biggest may contain tens of millions of residents. “They’re really lovely,” says MacDonald. “They look like topiaries.” Flushed with blood, plumes blossom from the top of each worm. Blood also colors the thin walls of the buried trunks. Hydrogen sulfide, lethal to most creatures, can enter either blood-enriched end. There gas blinds with a specially adapted hemoglobin, Which carries it to symbiotic bacteria. As the base rock becomes impenetrable in very old communities, the worms in the center likely die when their access to hydrogen sulfide is cut off. Like seep mussels , tube worms attract visitors. Squat lobsters, such as the one grazing above, nibble bits from the plumes and leave them ragged.