Fast moving worm. Not a flatworm

[Riotjj21]

Fast moving worm. Light front dark back. Stripe separating front and back. Not a flatworm. Good bad or indifferent?

 

[Riotjj21]

Fast moving worm. Light front dark back. Stripe separating front and back. Not a flatworm. Good bad or indifferent?

There were lots of them congregating under a rock.

 

[Crabs McJones]

Baby stomatella?

 

[Riotjj21]

Don't think so. No shell. Did you watch the video? Clearer in the video