An Elder Thing.

The Elder Things were the first alien species to come to the Earth, colonizing the planet about one billion years ago. The Elder Things exhibited vegetable as well as animal characteristics, and in terms of reproduction, multiplied using spores, although they discouraged increasing their numbers except when colonizing new regions. Though they could make use of both organic and inorganic substances, the Elder Things were preferably carnivorous. They were also amphibious.

The technology that the Elder Things possessed was not described at length, but was described as being extremely advanced. On Earth, the Elder Things built huge cities, both underwater and on dry land. They may be responsible for the appearance of the first life-forms on Earth, including the entity known as Ubbo-Sathla(although sources differ in this regard). They bio-engineered the dreaded Shoggoths to be their all-purpose slave race. Eventually, however, the Shoggoths rebelled–an event that hastened the decline and ultimate collapse of their civilization.

They are known to have warred against the Cthulhi, the Great Race of Yith and the Mi-Go. Despite these conflicts, it was the gradual cooling of the planet during the last ice age that spelled their doom. Retreating to their undersea cities deep in the ocean, they would thereafter have no further dealings with the outer world. Their last surface city, located on a high plateau in the Antarctic, remains frozen in ice. The ruins of this city were discovered in 1931 by two members of an Antarctic expedition from Miskatonic University .