• (n.) The tissue which fills the interspaces between the costae of many madreporarian corals, usually consisting of small transverse or oblique septa. Found on http://thinkexist.com/dictionary/meaning/exotheca/
Ex`o·the'ca noun [ Nl., from Greek 'e`xw outside + ... a case, box.] (Zoology) The tissue which fills the interspaces between the costæ of many madreporarian corals, usually consisting of small transverse or oblique septa. Found on http://www.encyclo.co.uk/webster/E/89