Actor Leonard Nimoy, best known for his role as Spock on Star Trek, passed away Friday morning at the age of 83.

For the past couple of months on Twitter, the actor appeared to be saying goodbye to his fans. The acronym LLAP, which stands for "live long and prosper" — appears in many of his tweets.








And maybe his most poignant recent tweet is possibly a reference to the smoking-related chronic obstructive pulmonary disease that took his life.