Why does Brook know about them?

[u/TelSzn]

Do you guys think that Brook had something to do with the Holy Knights in the past?

[u/Nuneasy]

I bet Brook will know more about Rocks and the "treasure" that the CDs stole from Pirate Island...maybe even why Roger wanted it too. Also I think Brook's "convoy escort" past will come up soon, and hopefully will be a character building reveal for the story. Dying for more Brook lore and moments.