Anyone know what this thing in my urine is?

I'm a 33M and had blood in my urine for 5 days before it cleared up. Urine tests showed no UTI, and a CT scan came back clear — no kidney stones, no bladder or kidney cancer. Blood work was normal too. It didn't hurt to pee and I had no back or belly pain. Still not sure what was actually causing the blood. And now even though the blood is gone, there's this red string/worm-looking thing. The photo is super zoomed in — in real life it's tiny — but what could it be? Has anyone seen anything like this? Any help is appreciated, thank you!