As the last and smallest of the gaseous planets in our solar system, Neptune is one of the least understood.  Named for the Roman god of the sea because of its striking blue appearance, Neptune's oceans are of liquid hydrogen and helium.

Neptune revolves around the Sun taking 165 years to complete its journey, yet one Neptune day takes 18 hours.  Prior to the discover of Neptune in 1846, the known solar system extended only 20 AU.  After Neptune's discovery, the solar system grew by 33.3% as far as humans are concerned.

Neptune, like Jupiter, has constant storms that churn its atmosphere in a never ending cycle.  In addition, Neptune also has a giant spot!

 
Approximately the size of Earth, Neptune's Great Dark Spot is a recent discovery by scientists.  Not much is known about it other than its cyclonic patterns
If life existed on Neptune, what would it look like and why?