Strange algae growing on snails-- is this harmful?

[dejaknu]

I bought these snails from the LFS 2 weeks ago. I noticed this red algae stuff growing on the light colored one when I first brought it home but figured the other would just eat it. Today I noticed it's growing on my other snail (below). Is it harmful/does anybody know what it is?

 

[Flippers4pups]

Looks like Coraline algae! Bouns!

 

[dejaknu]

Thanks for the reply, @Flippers4pups! Here's another photo. I'm talking about the hairy parts. Is that coralline algae?

 

[StatelineReefer]

Looks like Gracilaria sp. Likely corticata or coronapifolia. Hard to tell until it grows out more. If it develops flat, broad 'leaves' it may be Hayi.