Hydrocoralia or Hydrocorallia: How To spell?
The word Hydrocoralia is misspelled against Hydrocorallia, a noun meaning "A division of Hydroidea, including those genera that secrete a stony coral, as Millepora and Stylaster. Two forms of zooids in life project from small pores in the coral and resemble those of other hydroids. See Millepora."
Hydrocorallia has double "ll" is mispronounced as "l"Remember double 'LL' in between the strings hydrocora & ia which should not be misspelled with single 'L'
Wrong Spelling:  hydrocora-l-ia  Correct Spelling:  hydrocora-ll-ia 
Find more incorrect spellings of Hydrocorallia to spell right way.