Worm I've never seen

I managed to suck it up with a turkey baster. It's a little under an inch long, and at first, it looked like this:

https://www.youtube.com/watch?v=3IHWUP6sVhQ

And then, in the amount of time it took my to upload that video and start posting this, I went back, and saw that it now looks like this:

https://www.youtube.com/watch?v=a01RgjN4w1M


Looks like it shed its blue coating. I'm assuming those are larvae? I'm wondering if this should just not go back in the tank...