There are different types of obstacles which can rotate after been hit by marbles. Most rotating obstacles are mounted on a pin inside the sand course, sometimes a wooden board is placed over the sand to reduce the chance that a marble will get stuck in front of the obstacle.
The rotating obstacle can push away marbles after been hit, marbles have better to avoid these nasty things.
This little wooden spinner has 4 wings and will simply rotate upon hit. Because of the little dimensions, it won't be a really threat unless been placed in the middle of a narrow course.
After been hit, this sign can swing away the oncoming marbles. It will be placed usually on wide track sections or in front of splits or other obstacles.