When my Jazz had tapeworms they looked like little short pieces of cooked spaghetti when alive and then they looked like little grains of rice when dead.

If you aren't sure just try to collect one next time you see and take it to your vet. I had never seen tapeworms before so I collected what I saw in a ziplock baggie, took it to the vet and they gave me a pill to bring home and give Jazz. In fact they gave me enough pills to treat my other cat at the time.