From endo- +‎ fauna.

endofauna (uncountable)

1. (biology) animals from outside of an organism's immediate environment.
   • 2015 July 10, “Biodiversity on the Rocks: Macrofauna Inhabiting Authigenic Carbonate at Costa Rica Methane Seeps”, in PLOS ONE‎^[1], →DOI:

     We set out to study these ecosystems at methane seeps with the hypothesis that diverse epi- and endofauna may rely on AOM for substrate settlement, refuge and nutrition.

• endofaunal