Those pictures do look like detritus worms. They are harmless but personally I find them unsightly. In a tank with fish the fish would just eat them, but its harder for some of our newt species to get them depending on what you are keeping. The easiest way to get rid of them is to add fish. If you are keeping an axolotl then this is not a great option as the axolotl will eat the fish. For any adult newt, adding a few white cloud mountain minnows will work and they will eat all your detritus worms within a few weeks.