 The discovery of Anomalocaris ( " abnormal shrimp " ) was a comedy of errors . The name was initially given to a fossil that looked like the rear end of a shrimp @-@ like crustacean . Walcott classified a ring @-@ like fossil he called Peytoia as a kind of jellyfish , and another poorly preserved fossil he called Laggania as a <unk> ( sea cucumber ) . After many plot twists , Derek Briggs started dissecting another ill @-@ defined fossil in very thin slices and found a pair of Anomalocaris @-@ like structures on one end of a specimen of Laggania , which also had a specimen of Peytoia attached just behind those of Anomalocaris . After dissecting more specimens and finding similar configurations , Briggs and Whittington concluded that the whole assemblage represented a single animal , which was named Anomalocaris because that was the earliest name assigned to any of its parts . This animal 's body was fragile and usually disintegrated before it could be fossilized . But the complete animal had tough grasping appendages ( Anomalocaris ) , a tough , ring @-@ like mouth with teeth on the inner edge ( Peytoia ) and a long , segmented body ( Laggania ) with flaps on the sides that enabled it to swim with a Mexican wave motion , and perhaps to turn quickly by putting the flaps on one side into reverse . This monster was over 2 feet ( 0 @.@ 61 m ) long when other animals were only a few inches at most . <unk> suggested in 1999 that the animal was capable of taking heavily armored trilobites apart , possibly by grabbing one end of their prey in their jaws while using their appendages to quickly rock the other end of the animal back and forth , causing the prey 's exoskeleton to rupture and allowing the predator to access its innards . In 2009 <unk> found that anomalocarid mouthparts showed little wear , which suggests they did not come into regular contact with mineralised trilobite shells . Computer modeling of the Anomalocaris mouthparts suggests they were in fact better suited to sucking on smaller , soft @-@ bodied organisms . Although Whittington and Briggs concluded that Anomalocaris did not fit into any known phylum , research since the 1990s has concluded that it was closely related to Opabinia and to the ancestors of arthropods . In 2009 a fossil named Schinderhannes bartelsi , an apparent relative of Anomalocaris , was found in the Early Devonian period , about 100 million years later than the Burgess Shale . Conway Morris gave Hallucigenia its name because in his reconstruction it looked bizarre – a worm @-@ like animal that walked on long , rigid spines and had a row of tentacles along its back . Science fiction author Greg Bear says the <unk> in his The Way stories were scaled @-@ up versions of this reconstruction . However , in the late 1980s Lars <unk> literally turned it over , so that the tentacles , which he found were paired , became legs and the spines were defensive equipment on its back . <unk> classified it as one of the <unk> , a phylum of " worms with legs " that is considered closely related to arthropods . Another current view is that Hallucigenia was an armored lobopod , in other words more closely related to arthropods than the onychophorans are , but less closely related to arthropods than Opabinia or Anomalocaris are . 
