Help, my newts aren't newts anymore!!!?

I hatched supposed "newts" out of eggs a month ago and have been raising them. They looked a little different than the newt larvae pics on the internet, but I thought they were. They are about 3/8 inch long. Today, I found out that they shed their skin and morph into another water-dwelling organism!!! I don't know if these are newts anymore. It turns out I was wrong. The larvae had black heads and long slender, segmented bodies. The new "organisms" (whatever they are) are dark brown, have large heads, and have a segmented tail that curls around their bodies. Both types are the same size, but they are definitely NOT newts. DOES ANYONE KNOW WHAT THESE THINGS ARE?? Should I throw them out or continue raising them? I NEED ANSWERS HELP!!!