First contact with aliens could end in colonization and genocide...

 https://theconversation.com/first-contact-with-aliens-could-end-in-colonization-and-genocide-if-we-dont-learn-from-history-207793

The ET phenomenon has been around for a very long time.

https://desertshapes.blogspot.com/search?q=ET+Crash+Retrievals Could some vehiclels be like a Trojan_Horse?

Fade to Black with Rick Doty

https://jimmychurchradio.com/fade-to-black-rick-doty

FTB Ep. 1833 Rick Doty: Recovered Alien Craft https://www.youtube.com/watch?v=Wy78Ji--wRA , https://www.youtube.com/@FADETOBLACKRadio

Talking about crashed and recovered ET vehicles can get quite interesting. How much is just speculation or conjecture? Over the decades, varios pilots and first responders have seen strange things in the sky that just don't seem to be like conventional aircraft, or any known vehicle. 

The concept of ET tech and Inter-dimensional craft is too mindboggling for many people to ponder. 

https://desertshapes.blogspot.com/search?q=ET+Crash+Retrievals

LMH: Strange Pings and ET Crash Retrievals

http://www.coasttocoastam.com/show/2016/11/23 , https://www.facebook.com/earthfilesnews
If some large tech is moving around the oceans, the general public will be the last to know.
http://www.cbc.ca/news/canada/north/ping-beep-hum-sound-arctic-ocean-igloolik-1.3831861
It could be intelligently controlled machines.
http://www.livescience.com/56759-mysterious-arctic-ping-investigation.html
Or, interplanetary vehicles poking around.
http://www.bbc.com/news/37875609
Perhaps even supplying deep sea and underground bases.
http://www.news.com.au/technology/environment/canadian-military-investigate-mysterious-sound-coming-from-arctic-seas/news-story/0262a19b08da9e1b1fce247f1e1d45ed
Some that might have been around since ancient times.
https://gizmodo.com/canadian-military-investigates-mysterious-pings-from-th-1788578162
Indeed, something might have been watching this world for a very long time.
http://www.newdawnmagazine.com/articles/enoch-the-watchers-the-real-story-of-angels-demons
Could the Watcher_(angel) be one of a class of sentient energy forms or inter-dimensional beings?
http://www.deliriumsrealm.com/watchers Various religions & myths can provide clues & hints about ancient history.
http://www.ancient-origins.net/human-origins-folklore/origins-human-beings-according-ancient-sumerian-texts The Earth could be someones laboratory experiment, school or prison.

http://www.crystalinks.com/libraryofalexandria.html
The Destruction_of_the_Library_of_Alexandria is a key point in time where a tremendous amount of data was lost.
http://www.biblicalarchaeology.org/daily/biblical-sites-places/biblical-archaeology-places/the-ancient-library-of-alexandria-
http://www.ancient-origins.net/ancient-places-africa-history-important-events/destruction-great-library-alexandria

Massive deep aquatic life forms are also something that the general public might never be informed of.
https://en.wikipedia.org/wiki/Bloop#Analysis
For many, its best to just consider the Bloop sound to be just another anomaly in the world.
http://www.pmel.noaa.gov/acoustics/sounds/bloop.html

http://weekinweird.com/2013/03/28/iceberg-unexplained-bloop-sound-worth-baffled/

http://www.wired.co.uk/article/bloop-mystery-not-solved-sort-of

https://io9.gizmodo.com/5962724/remember-that-scary-undersea-bloop-noise-at-last-we-know-what-caused-it

Officially, no one wants to say that ET life might have been around for more than the equivalent of a few billion years.
https://en.wikipedia.org/wiki/Wow!_signal
And that some of that ET life might have been watching and occasionally tinkering with this world & others for a very long time.
https://www.theguardian.com/science/across-the-universe/2016/apr/14/alien-wow-signal-could-be-explained-after-almost-40-years

http://www.space.com/33904-seti-mystery-signal-wow-alien-message-debate.html

https://www.earthfiles.com , https://www.youtube.com/user/Earthfiles , http://www.earthfiles333.com
So much of this world & universe remains a mystery but most people are too busy to notice.
http://www.ancient-origins.net/unexplained-phenomena


https://desertshapes.blogspot.com/search?q=ET 

https://desertshapes.blogspot.com/search?q=mysterious+places