Found this guy in my sump

[burtonboy182]

Found him in my sump this evening. He was in with the Cheato climbing on the wall. He is about 1/4 - 1/2 Inch
Thanks

 

[Jay Tosi]

Some kind of sea squirt? if so he will actually filter your water

 

[C. Eymann]

Does it have a shell? if so limpet would be my guess, if no shell- polyclad flatworm maybe?

 

[AdamB]

+1 on sea squirt

 

[vetteguy53081]

acoel flatworm which is common in sumps. Not considered harmful BUT no flatworm is invited in my tanks.

 

[C. Eymann]

acoel flatworm which is common in sumps. Not considered harmful BUT no flatworm is invited in my tanks.

Looks a bit large to be a acoel flatworm

I'm betting it's a polyclad FW, that is if OP doesn't report it having a shell.

If it has a shell- limpet would be my guess