"EXTRATERRESTRIAL" is not applicable. It is, by definition "not of this world". Posit: A race of beings that predate 'us', relocated to the depths of the oceans to survive the last ice age. Then following a cataclysmic event - emerged to repopulate civilization(s) with technology exceeding ours - at the time. And since then, come an go from their submarinal domain, becoming detectable by our advancing state of technology. [If..?] They're here... what do we call them..?
"Retroterrestrial"..?
"Ancienterrestrial"..?
Who's Your Daddy..?
"Retroterrestrial"..?
"Ancienterrestrial"..?
Who's Your Daddy..?