Nasa's Unexplained Files: Earth's Secret Aliens
04:00 am - 05:00 am, Sunday, August 9 on Quest +1 (70)
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Earth's Secret Aliens
Season 3, Episode 20
Geologists begin to ask questions about 'alien' deposits found on the Earth's surface - and the answer could shed light on the cause of history's greatest extinction event
HD
subtitles
16x9
Education/Science/Factual Topics
Unexplained/Mysteries
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