Cutie mark of one of my most favorite and obscure background ponies. The two ends should always face the same way he does, or as my friend VectorizedUnicorn puts it, the curve of the moon should curve with his rump. Therefore, this should be mirrored if he's going to be facing to the right, or basically if you are going to place this cutie mark on a right flank. Princess Luna's cutie mark functions the same way, if you need another reference.