De facie quae humano vultui

[Inter master]

Hello. I've been trying to do some translations lately and most of them were successful. Also, I got to the point where I am questioning myself for some examples. I have some abbreviations, but I guess that must exist at some point.
Anyways, there is a sentence which says: ,,De facie quae humano vultui simillima in orbe lunae apparere solet disputaverunt".
It refers to "them".
Now, I do understand the meaning of the words and I do understand that something is similar to something.
I would try with: They were arguing about the appearance of the Moon, which is similar to a face of a human and it usually shows in a circle or a round shape, not sure about that, though.
Could you, please, help me to figure this out properly?
Thank you.

 

[Iáson]

A few things:

They were arguing

disputāvērunt is perfect tense, not imperfect.
quae opens a relative clause, and lūnae is inside that clause, dependent on orbe: 'in the disk of the Moon'. If you take faciēs in the sense of 'face' rather than 'appearance' it might fit together better.
I think it's a restrictive relative clause.

 

[Inter master]

Thank you for helping.