Planet or Origin: Neptune (or more probably, its moon Triton)
The Tritons are a peaceful amphibian species of cephalopods which developed an advanced civilisation capable of space faring. They possess 6 tentacular limbs, two of which are more muscular and used for on-land navigation as a tentacular trunk on their head.
Men of Neptune action figures where commercialised in the sixties. Their story was told at the back of their blisterpack:
Deep beneath the stormy seas of Neptune, great citiesloom majestically in the shimmering twilight of a vast and beautiful warer world. Here the mighty Triton. People live. Not content to see the sun as but a shimmer and the stars as tiny ripples glowing on the surface of the sea above, Astronautilus and his band of Triton mariners venture forth to sail and chart that greater ocean, Outer Space. Often visiting our planet they land, secretly, without all human knowledge, in the depths of Earth's great oçeans.
Source: Mel Birnkrant, The Outer Space Men – also known as the Colorform Aliens, 1968.