It’s the exploding tag; a part of the basic equipement of the shinobi. If you see it on the field, try to pick it up!

As on might expect, the tag will explode after thrown. But not immediately…

After the tag hits something, it will first stick in place for a while. This could give you the time to dodge the explosion it releases, but your timing has to be very accurate for that…

Don’t fool around with the exploding tags too much though. They are weapons, not toys. If you play around with them, they might explode prematurely.