Bad or benign flatworms?

[laezur]

Hundreds of these buggers on the glass now.

They are all the same, grey bodies with what appears to be a red speck where I assume their mouth is

 

[T-J]

While they aren't a direct threat to corals, they will reproduce quickly and can smother corals from light. They will cover the coral which will starve out.

 

[laezur]

While they aren't a direct threat to corals, they will reproduce quickly and can smother corals from light. They will cover the coral which will starve out.

Guessing these aren’t the super bad red ones then?

can I scrape my glass to get algae off without worrying about killing them all and crashing my tank?