Hi all I recently purchased a GSP a few days ago and noticed a white tube on the mat when the polyps are retracted, can’t really see it when the polyps are out which is why I didn’t notice in the store. From looking at older posts here I believe it is a fan worm because it will also have the clear little tentacles come out of it. I will be posting pictures of it. A couple questions if it is a flat worm. Do you leave it alone so I don’t harm the GSP? Can they spread around the tank? Thank you.