Are these aquarium rocks safe?

[Brickosaurus]

I think the red rock looks cool,despite its resemblance to my favorite food group. Seeing the striations from its formation is fascinating. I like to nerd out on rocks even though i know little about them

Same. I'll make sure it's clean then I'll put back in, I personally love the look as well!

 

[Joshuakahan]

Same. I'll make sure it's clean then I'll put back in, I personally love the look as well!

If you have enough, they would make a cool background

 

[Brickosaurus]

If you have enough, they would make a cool background

I wish I did. But I only have this one sadly