Algae identification

[MWrasse]

What type of algae is this? It won’t come off with a toothbrush. It’s so stuck the only way to get it to come off is to scrape with tweezers. It looks like scales.

 

[Dan_P]

What type of algae is this? It won’t come off with a toothbrush. It’s so stuck the only way to get it to come off is to scrape with tweezers. It looks like scales.

Pictures nor quite in focus. I’ll guess that the algae is Ulva, sea lettuce.