Tow basic body forms of cnidaria: medusa and polyp.
Ref: <cite class="book" style="font-style:normal">Ruppert, E.E., Fox, R.S., and Barnes, R.D. (2004)      <i> Invertebrate Zoology</i> (7<sup>th</sup> ed.), Brooks / Cole, pp. 111−124  <small><a href="https://en.wikipedia.org/wiki/International_Standard_Book_Number" class="extiw" title="en:International Standard Book Number">ISBN</a>:  <a href="//commons.wikimedia.org/wiki/Special:BookSources/0030259827" title="Special:BookSources/0030259827">0030259827</a>. </small></cite>
<a href="//commons.wikimedia.org/wiki/User:Philcha" title="User:Philcha">Philcha</a>
<span class="int-own-work" lang="en">Own work</span>