What's this on tank glass?

[Allybobo]

Hi guys, I suddenly found some small creatures on my tank glass and they are eating like a snail (but without shell). What are these? Should I keep them or eliminate them?

 

[Allybobo]

It is eating the copepods on glass

 

[TheBear78]

My money is on it being a Flatworm.
There are mixed opinions on their desirability in a reef tank but hopefully someone else can chime in.

 

[Allybobo]

I found similar pictures and this seems to be "ghost flatworm" (Amphiscolops sp.). It's said to be reef safe so I'll keep them there. They look cute.
https://humble.fish/community/index.php?threads/hitchhiker-identification-guide.3687/

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