Caltrops

The Caltrops is a device with four metal points arranged as a hazard to the hooves of horses or to tires.

Behavior
Well this object collides with anything, it will deal 20 points of damage and instantly disappear. This object doesn't collide with living and vehicles, only interacting with certain objects. This object has 50 health points, weights the same as spider and sinks underwater. It is considered a ninja weapon, but Ninjas won't equip it.