What is this and how to get rid of it?

[DaddyO NJ]

 

[DaddyO NJ]

Forgot to write- it’s kinda clumpy and sticks to sand, but is easily scooped up in a net. First attempt with siphon did not have enough of a siphon. Going to try again tonight. I did a round of chemiclean which helped a little , but cam right back.