Harmless worm, or parasite???

[ToddTT]

I just noticed a super thin, 1/4 inch white worm climbing the glass of my tank. It is just a little bit thicker than a thread.

Is this just something random that crawled out of the rock in my tank, and okay? Or is it possibly something bad, like a parasite?

[Steve McKay]

Need a good photo for ID.

[ToddTT]

Need a good photo for ID.

I'll look for him again today.

The picture would not have been too interesting, just showing what looks like a 1/4 inch piece of white thread. More thread-like than string, as he was very skinny, with no other features to speak of.

However, maybe to see it in action would be more informative. It seems like it lengthens very slightly, and contracts, as part of its movement.

Also, last week I also saw a slightly longer one, maybe 1/2 inch, attached to a rock. It too would lengthen and contract, reaching off the rock like it was looking for something.

I'll hopefully be able to snap a picture later today.