Wow. It's not something I am familar with, but there are many parasites hard to identify by a pic. It does not look like something you would find in a tub or brought in from outside......and it actually does look like something intestinal/moucousy.
The thing about parasites is that they do not easily fall from within the body easily. So, again, IF it is a parasite, there are probably more, and a gentle enema might bring more out.