These roots are normal on stem plants. it is most commonly seen when theres not enough nutrients in the substrate and it is trying to draw some out of the water column. It still occurs when there is enough nutrients but just not a lot.
If you cut them they will still grow
Then I saw it. I saw a mom who would die for her son. A man who would kill for his wife. A boy, angry and alone. Laid out in front of him, the bad path. I saw it. And the path was a circle. Round and round. So I changed it.
-Joe (Looper 2012)