Doug Perrine / Tornaria larva of the acorn worm or enteropneust worm (Ptychodera flava) photographed at night in surface waters of deep ocean off Kailua Kona, Hawaii, USA.
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Graham Eaton / Fossil Graptolites (Didymograptus murchisoni) with lens cap for scale, Ordovician, Llanvirn age, shale at Abereiddy, Wales, UK, June.
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Juan Manuel Borrero / Illustration of hemichordate worm (Hemichordata) in burrow. Pencil, watercolor and pastel illustration
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David Fleetham / Acorn worm (Enteropneusta sp.) or Hemichordate worm (Hemichordata sp.) larvae swimming in open sea at night, Yap, Federated States of Micronesia, Pacific Ocean.