Flatworm or algae?

[inkandcaffeine]

After some travel (excuse the green on the back of the tank) came home & was looking at my rock & saw these guys?? Any clue what they could be? only have soft corals, snails, herms & clownfish in the tank, but got some corals a few months back from lfs & probably had some hitchhikers, help would be lovely

 

[Kingsley_Reef]

Flatworms for sure

I have had luck in the past dipping rock and coral In rodi and they come right off

 

[Tahoe61]

Flatworms, that's a problem.