This interesting form is created when yogis do a pose called the rabbit pose. I have been mystified as to why it is called that. Searching for an answer I eventually found this explanation from Yoga International magazine:
βRabbit poseβalternately called hare pose, hare headstand, and sasangasana (sometimes written shashankasana)βis an asana that evokes nostalgia for childhood playfulness, a deep connection to nature, and the calm gentleness of bunnies.
In Sanskrit the moon is called sasanga, βhaving the marks of a hare.β If we were to look closely at the moon, perhaps we could find a rabbit-like shadow, and the curled roundness of this pose reflects both moon and rabbit in shape.β