Thalasian or Thalassian: How To spell?
The word Thalasian is misspelled against Thalassian, a noun meaning "Any sea tortoise."
Thalassian has double "ss" is mispronounced as "s"Remember double 'SS' in between the strings thala & ian which should not be misspelled with single 'S'
Wrong Spelling:  thala-s-ian  Correct Spelling:  thala-ss-ian 
Find more wrongly spelled words of Thalassian to spell it well.