I did the same n it was black n stinky. To
fix this I put them in tap water and added bleach n let it sit for 4 days, than soaked for 2 days in tap with amquel n then Rodi overnight n stuck the ones I wanted into my DT.
i had the same happen to bin full of rock. Soaked in bleach for a couple days then RO for a few days with a small powerhead to provide circulation. Placed in tank right after. No issues.