Notice that there is a the stone which is already down on the ground. This is a rare occurrence. Portugal and Spain are among the few other countries showing this feature. In both countries the boulder has been deformed by the impact.
The German artist, however, froze the movement at the very moment of touching down, just before any distortion could happen. That explains also why the stone seems to balance on one of its short sides.
Our last sample is not easy to interpret. It all depends on the meaning of the huge black dot. If this dot represents a rock then we are looking at a Fallen Rock Sign. If not then the find can't be part of the collection.
A similar sign which is clearly no Falling Rock sign — because the caption says dāng xīn zhuì luò — is reported from Hanzou, China: in that case no boulder is shown next to the person. Other people falling down accompanied by rocks were found in f.e. Faeroe and Canada.