Clastra or Claustra: How To spell?

The word Clastra is misspelled against Claustra, which is plural of "Claustrum"

Word contains consecutive vowels 'AU' in between alphabets cl & stra is misspelled as 'A' as letter 'U' is phonetically ignored
Wrong Spelling: cl-a-stra
Correct Spelling: cl-au-stra
Browse incorrect spellings of Claustra to spell it good.