What is this?

[adespain81]

I saw this on my sea hare. I also saw another one floating. It looked red when in the water. Sorry. This is the best Pic I could get.

 

[ISpeakForTheSeas]

I saw this on my sea hare. I also saw another one floating. It looked red when in the water. Sorry. This is the best Pic I could get.

Looks like some kind of macroalgae to me.

 

[stewy14]

(just came here to say that)