The picture is fine. Looks like a macro algae, some type of Halimeda I believe. It should not be a problem such as seen with the taxifolia that is invasive if it gets into local water supplies, but still put it in a bag or something, if you throw it out, never dump it into the drain locally.
Keeping it in your tank will just help eat up extra nutrients and thus prevent more ugly looking micro algae to settle on your corals, which can be very bothersome to some corals. Keep it and trim it if it grows beyond what you like. It can be hard it introduce macro algae into a tank anyway because leafs will die if they cannot get nutrients equal to what they are grown on.
This way you just grew some macro algae naturally and now you won't have to consider buying some from your local LFS if you get a nutrient problem later on because then this will grow and you can trim it and remove nutrients from your tank that way.