I have accidently swallowed the top thing that opens a can. is it dangerous or will my system will get rid of it without danger? concerned please! er

Should be pooped out: Teens or adults who accidentally swallow such objects usually just poop them out without problems. Fortunately, the pop-top pull-piece is generally attached to the can (in the old days, the piece was pulled off and separately thrown away, which meant the chance of it ending up in a bad place was a lot higher). The pop-top pull-pieces tend to have rounded edges, which helps them get pooped out.

Depends: If it hangs up in your swallow tube it can/will be a problem. If it made it to your stomach it will likely pass through over several days. If you can drink fluids without choking it would be in your stomach. If you consume stewed okra it will form a bit of crud around the edges & let it pass easier. If you can't be sure go to urgent care where they can x-ray to find out where it is.