The term, Marichi's pose, comes from the fact that it is dedicated to the sage, Marichi, from Hindu mythology who is also the son of Brahma.
Marichi's pose C is good for the back, like all twists, because it helps to improve spinal flexibility and brings circulation to the spine. The main twist should occur through the thoracic spine, not the lumbar spine, in order to avoid injury to the lower back. It can be modified with a belt between the hands to improve the reach and can also be performed without binding the arms around the back at all. The hips can be raised by sitting on a folded blanket or cushion.
This pose also stimulates the abdominal muscles and organs, relieving constipation and other digestive issues.