Suddenly-arrived plant in pond - friend or foe?

[Dillybythesea]

Rather a murky pic, sorry, but I wonder if anyone can say anything about this plant - of which several have suddenly appeared in different spots in our nature pond, submerged, about a foot to 18ins down. It doesn't look like anything I've introduced/ planted as a marginal. We have a butyl liner so, whatever they are, they've set themselves up in the natural sediment that has built up, and seem to be growing rather fast. I carefully fish out blanket weed and duckweed to keep things under control, and am wondering if this is something else to add to the list? Or might it be a 'good plant'? Any input gratefully received! I should add that I mean the star-shaped plant on the right, a bit like a spider plant.

[JohanJ]

Hair grass?

[Dillybythesea]

Originally Posted by JohanJ

Hair grass?

Having googled that, I'm thinking you could be spot on! And as a native it looks OK! Though I'll google it again tomorrow to be sure! Thanks for the input!