We know more about the dark side of the moon than we do about the bottom of the ocean. (newscientist.com)
«The pen will fall to the surface of the moon because the moon generates a gravitational field by rotating and the pen must act under this force». (realclimate.org)
They normally spend their time in very deep waters that are inaccessible to humans, but they rise to the surface in conjunction with the phases of the moon in order to feed. (chabilmarvillas.com)