▁large ▁study ▁in ▁ 2 0 0 8 ▁by ▁D unn ▁et ▁al . ▁strongly ▁supported ▁the ▁E cd y so zo a ▁as ▁a ▁cla de , ▁that ▁is , ▁a ▁group ▁consisting ▁of ▁a ▁common ▁ancest or ▁and ▁all ▁its ▁descend ants . ▁ ▁The ▁group ▁is ▁also ▁supported ▁by ▁morph ological ▁characters , ▁and ▁includes ▁all ▁animals ▁that ▁grow ▁by ▁e cd ysis , ▁m oul ting ▁their ▁ex os ke leton . ▁ ▁The ▁group ▁was ▁initially ▁cont ested ▁by ▁a ▁significant ▁minor ity ▁of ▁bi olog ists . ▁Some ▁argued ▁for ▁group ings ▁based ▁on ▁more ▁traditional ▁tax onom ic ▁techniques , ▁while ▁others ▁cont ested ▁the ▁interpretation ▁of ▁the ▁mole cular ▁data . ▁ ▁Et ym ology ▁ ▁From ▁An cient ▁Greek ▁ ἔ κ δ υ σ ι ς ▁( ék d ysis , ▁“ sh ed ding ” ) ▁+ ▁ ζ <0xE1> <0xBF> <0xB7> ο ν ▁( z ō on , ▁“ an imal ” ). ▁ ▁Character istics ▁▁ ▁The ▁most ▁notable ▁characteristic ▁shared ▁by ▁e cd y so zo ans ▁is ▁a ▁three - layer ed ▁cut icle ▁( four ▁in ▁T ard igr ada ) ▁composed ▁of ▁organ ic ▁material , ▁which ▁is ▁period ically ▁mol ted ▁as ▁the ▁animal ▁grows . ▁This ▁process ▁of ▁mol ting ▁is ▁called ▁e cd ysis , ▁and ▁gives ▁the ▁group ▁its ▁name . ▁The ▁e cd y so zo ans ▁lack ▁locomot ory ▁c ilia ▁and ▁produce ▁mostly ▁am o eb oid ▁s perm