zootheciumhttp://www.oed.com/dictionary/zoothecium_n%3Ftab%3Dmeaning_and_usezoothecium, n.
Revised 2017

zootheciumnoun

Now rare.
  1. 1880–
    An aggregate of the fused shells or protective sheaths of certain aquatic colonial protozoans; cf. polythecium n., zoodendrium n.
    1. 1880–1
      For these aggregations of..simple loricæ the distinctive title of zoöthecia has been adopted.
      W. Saville-Kent, Manual of Infusoria vol. I. 61
    2. 1895
      Social, forming a compound branching zoothecium. Genus Dinobryon.
      19th Annual Rep. Boston Water Board 1894–5 77
    3. 1963
      Zoothecium, zoocytium.
      I. F. Henderson & W. D. Henderson, Dictionary of Biological Terms (ed. 8) 637/2

Originally published as part of the entry for zoo-, comb. form

zoo-, comb. form was revised in June 2017.