Leonard Nimoy has been remembered since his death last week by celebrities, by Trekkies and by fans alike. However, one of the most poignant homages came from the CBS show The Big Bang Theory.

Thursday night’s episode ended with a black-and-white portrait of Nimoy with the words, “The impact you had on our show and on our lives is everlasting.”

Leonard Nimoy and his character, Mr. Spock, were in a way secondary “characters” on The Big Bang Theory with the number of references on them throughout the series.

Sheldon, played by Jim Parsons, has a real connection with Leonard Nimoy. In one particular episode, Sheldon receives a gift of a lifetime — well, his anyway — a napkin used by the Star Trek actor.

“I possess the DNA of Leonard Nimoy?!” Sheldon exclaims in the episode.

.@BigBang_CBS pays tribute to late #StarTrek icon #LeonardNimoy: http://t.co/BViqW3UI2S pic.twitter.com/StRArMXvP3

— Yahoo TV (@YahooTV) March 6, 2015

Today, we salute the legendary Leonard Nimoy #LiveLongAndProsper http://t.co/nA0tG8C61g pic.twitter.com/7N3NlDX7vf

— The Big Bang Theory (@BigBang_CBS) February 27, 2015

Get a closer look at the #BigBangTheory's tribute to #LeonardNimoy. http://t.co/aYKnNsdpV7 pic.twitter.com/a2Pc7gzszj

— The Big Bang Theory (@BigBang_CBS) March 7, 2015

Leonard Nimoy even made a cameo on the show during its fifth season.