Just given the shape they look like detritus worms. They move by wiggling into this shape. In general though they live in substrate and filters. Totally harmless, most fish will eat them.
Gotcha thats what I was thinking, but she seems to be kinda freaking out so wanted to reassure her. I havent seen any in my tank but she says they were from the plants🤷♀️ so seems like not a huge deal all around