Rob Dyrdek looked back on his friendship with Christopher "Big Black" Boykin, who died Tuesday at the age of 45, in a series of Instagram posts shortly after news broke of the beloved Rob & Big star's passing. Sterling "Steelo" Brim and Chanel West Coast, who both appeared alongside Boykin on Dyrdek's Fantasy Factory, also mourned Boykin's death with messages of remembrance.

"My heart is broken," Dyrdek said. "I don't want to write this post. I don't want to believe that this is reality. I am so thankful for you. We truly were brothers that lived an unexpected unforgettable adventure. I just can't fathom that it would end so suddenly. You will forever be in my heart."

Dyrdek also shared memories of his friend, including a photo of his son and Boykin enjoying a moment together:

 

💔

A post shared by Rob Dyrdek (@robdyrdek) on May 9, 2017 at 8:47pm PDT

 

I am so thankful for this moment... thank you for being an amazing human being and brother.

A post shared by Rob Dyrdek (@robdyrdek) on May 9, 2017 at 8:30pm PDT

 

🙏🏼🙏🏿

A post shared by Rob Dyrdek (@robdyrdek) on May 9, 2017 at 8:09pm PDT

Steelo remembered Boykin as an "overall great guy" who was "genuine" and "funny." Chanel, sharing the same photo as Steelo, said she would "never forget" all the times Boykin made her laugh.

Rest in power, Big Black.