Sentence:  Like a philosopher, or rather the hermit crab, he [Hoo Keng Tuck] lives in complete retirement, looking out occasionally from his coign of vantage upon his luckless compatriots who are struggling to make this world a better place to live in for themselves and their children, pretty much as a <WSD>Martian</WSD> might watch the social activities of the earth's inhabitants. 
Meaning of the word marked with <WSD> tags:  An inhabitant of the planet Mars.