The aliens (extraterrestrials) have been here awhile, it seems
And in a moment of synchronicity, I read this, later in the day, in a TLS review [7/31/15, Page 13] by Anne Magurran of Helen Scales book about mollusks: Spirals in Time: The secret life and curious afterlife of seashells [Bloomsbury, $27]:
"Cephalopods [such as octopus and squid] are the most highly intelligent invertebrates."
This means, for me, that octopuses (and squid), often featured in sea tales attacking ships, may have been deposited on Earth, millennia ago, by ET visitors, hoping they'd evolve, perhaps, into a viable, intelligent, operative species -- maybe even replicating the alien species that dropped them here; that is, the octopus or squid species mimic the look/thought of the species that brought them here.
Is there UFO lore where persons saw creatures that had tentacles?
Graphic (above) from: http://wall.alphacoders.com/big.php?i=369480