Their origin is unknown.
They are often sighted in the northwest of the USA (specially in the Oregon area).
They have a special interest about Earth's oceans and are known to have underwater ships (aka USO's).
In the 1980's and the 1990's they almost crashed a few times against US Navy ships while the americans were testing new sonar and radar systems.
They are peaceful and mostly nocturnal.
Last sighted in the year 2000 near San Francisco, USA.