I found this please ID

[latinreefer]

View attachment 5127
Not sure what this is on my glass, does anyone know what this is? Harmless or Not?

 

[Top Water]

Harmless usually in sump around rubble I just call them worm things

 

[trackfast]

I have some of those. They seem harmless; don't appear to bother any corals.

 

[latinreefer]

Thank you guys !!