From the Notes of Nikan Shrubcover: Concerning Ekron

Ekron, the capital city of the Zaphonite Empire, is bounded on the north by a strange crescent of mountains. These craggy peaks, known as the Lunar Mounds, extend south out of the Pillars of Heaven. 

The Lunar Mounds form a nearly perfect crescent shape and end so abruptly that there is a genuine debate among Burrow scientists as to whether this geographic feature is natural or a creation of Zaphon.