Though a charity commitment in Florida may have kept him from attending the funeral of his longtime friend Leonard Nimoy, William Shatner held an online memorial of sorts for his Star Trek co-star, who died Friday at 83.

On Sunday, Shatner posted several tweets in Nimoy's honor while also fielding questions from fans.

I feel really awful. Here I am doing charity work and one of my dearest friends is being buried.

— William Shatner (@WilliamShatner) February 28, 2015

Leonard and I seemed to be bound by fate to be friends. We were born 4 days apart. #LeonardNimoy

— William Shatner (@WilliamShatner) March 1, 2015

"@pasutcliffe: What life lessons did you learn from each other? #LeonardNimoy" I learned to be more serious I think he learned to be less.

— William Shatner (@WilliamShatner) March 1, 2015

"@AZGrobie: Is it true he disliked being called Len & other nicknames? #LeonardNimoy" I called him Lenny in private he never said anything,

— William Shatner (@WilliamShatner) March 1, 2015

Shatner also responded to fans and members of the media who were criticizing him for missing Nimoy's funeral.

I chose to honor a commitment I made months ago to appear at a charitable fundraiser. A lot of money was raised. So here I am; tell me off.

— William Shatner (@WilliamShatner) March 1, 2015

Nimoy was laid to rest in Los Angeles on Sunday. The New York Post reported that Shatner did indeed fly to L.A. and arrived before the funeral was set to begin; however, it's unclear whether he actually made it to the service.

Read more of Shatner's memories of Nimoy on his Twitter feed.