Flatworm?

[ferchb]

Had the tank 6+ years. Never noticed anything like this guy moving around. Last fish died a few months ago. Figuring out a stocking plan. Additions since then were 5 turbos, 5 zombies, a peppermint and a emerald crab. Any input is appreciated.

 

[NY_Caveman]

Does look like a flatworm.

 

[KJ]

Acoel brown flatworm.