Anyone know what this is?

[mdbronco]

The seller thought it might be Dragon's Breath but it doesn't really look like it to me.

 

[Sashaka]

The seller thought it might be Dragon's Breath but it doesn't really look like it to me.

Rhodophytes. Looks like Dictyota or Fauchea species to me.
Here are a few links to compare:
https://www.toppr.com/guides/biology/plant-kingdom/algae/
https://www.reef2reef.com/threads/red-macro-algae-plague-red-dictyota-how-do-i-get-rid-of-it.194184/
https://www.mysaltwaterfishstore.com/macro-algae/