From Dragonball Online Wikipedia
The combat caste. These are Nameks who are proficient in combat, and their power levels are usually around the 3,000 range. As stated previously, Nail is by far the most powerful warrior-type Namek, with a power level of 42,000. Warrior-type Nameks are unable to use some of the magician-like abilities of members of the Dragon Clan, as shown by how when Piccolo merges with Kami and uses his body as the base, the Dragon Balls lose their power and another Dragon Clan member (Dende) is needed to restore it. Nameks are an extremely resilient race and capable of healing themselves and regenerating body parts instantly, as long as their brains are intact. This does not make them completely invulnerable, though, as it takes a large amount of reserve energy to perform and it is possible for a Namek to die with his body more or less intact after a battle.The FUNimation Dub of Dragon Ball Z: Lord Slug explains that some extremely powerful Namekians found the ancient secret to unlocking a higher consciousness within, becoming "Super Nameks". These Super Nameks were extremely aggressive and very different from their agrarian counterparts.
Nameks are humanoids with slug-like characteristics, including antennae, light green skin, and pink patches appearing throughout their bodies (also, many Namekians are named after words meaning "slug" or "snail"). Elderly Nameks have darker green skin and less prominent pink patches (these appear to become dull-orange as the Namek advances in age), pointy ears, and red rings, in which they have three red conjoined rings on their ankles and wrists, making them look like they have ankle bands and wristbands. In Dragon Ball Online, the new generation Namekians have a yellow face and a vertical line in the middle of the head.