The Melnorme (pronounced /'mɛlnɔːmeɪ/), as far as we know, are a race of traveling traders in information and technology. They appear as several yellow globs piled on top of each other, with a large smile and a single eye.
The Melnorme's basic culture revolves around exchanges of items, information, and commodities. They believe that giving without receiving is barbaric. The Melnorme lustly search for new information about biological creatures and the ominous Precursor Rainbow Worlds, but to what end is unknown, although, it is probably safe to assume that they sell the information to someone else.
Melnorme are highly sensitive to color. Their bridge has a colorful background that changes to fit their mood or activities. Red is for travel, purple is generally assumed to be for trade (if one manages to find enough credits the Melnorme might even sell the information about turning purple) and when you meet a Melnorme with a blue bridge, know that he is locking his weapons systems on your ship.
The similarity in name between "Melnorme" and "Mael-Num", combined with the fact that the Mael-Num are being described as one-eyed creatures, may lead one to suspect there is a connection between the two. And indeed, Paul Reiche III and Fred Ford have confirmed that the Mael-Num are ancestors of the Melnorme.
The Melnorme are never found in Hyperspace (unless they come looking for you) and are generally encountered only around supergiant star systems. A Melnorme with the name Trademaster Greenish is always located in every supergiant star in the quadrant.
The Melnorme's Trader ship, while not designed as a warship, is still capable of defending itself. Its charging Powerblaster Fearton Torpedos are known as the one thing that can actually absorb an Ur-Quan Fusion Blast and the Confusion Ray is capable of half crippling a ship's navigation and special systems.