Donato,
From what you are describing it's probably pieces of mucosal lining.
Are you having mucuous and blood too?
I would suggest your being proactive about the inflammation.
That would mean a whole slew of things: rectal meds, adding certain supplements, diet modification, probiotics, slippery elm powder, l-glutamine, etc....
If you are interested, there are things IMO that you can control, which will have a direct impact on
your disease, the symptoms you experience and their severity.
I was able to control my UC into remission through various
supplements, probiotics, diet modification, and LDN , low dose
naltrexone.
For more info on the protocol which has put me into remission,
please go to this link: https://www.healingwell.com/community/default.aspx?f=38&m=1666318 , and look at the 11th post.
I hope you feel better and let us know how we can help
you.