Caltrop

Caltrops are small metal devices that have four pointy legs sticking out. They look like a very spiky star when you look at them from the top. And when you put them on the ground, at least one leg will always be sticking up into the air.

Now, imagine you're running around trying to escape from someone chasing you, and you step on one of these caltrops. Ouch! It's like stepping on a bunch of sharp needles all at once!

So, people use caltrops for two main reasons. First, they can use them as a weapon to hurt others, especially those who are trying to chase or follow them. Second, soldiers use caltrops as a way to slow down their enemies who are trying to attack them, as it can puncture the feet or wheels of the attacking force. This is because if you have a lot of sharp caltrops on the ground in front of you, your enemy will have to be very careful as they walk, and they'll probably slow down a lot.

Overall, caltrops are not very friendly things to deal with, and it's always a good idea to avoid them if you see any lying around!