Nu

Water summons wind... wind makes fire dance...
The Nu are quite possibly the most enigmatic creatures in Chrono Trigger. Despite their low HP, theydo have a very powerful attack that will instantly reduce a characters to 1 HP, no matter what thecharacter's level. Belthasar has a Nu assistant at the Keeper's Dome, who helps Crono becomefamiliar with the Epoch. The Nu are often seen by fans of the series to represent the power of theplanet at work, or perhaps its life force -- which explains their combat capabilities nicely, inthat the planet is powerful, but is malevolent only when it has to be to defend itself. There aresix Nu in 12000 B.C., all of them inhabiting Zeal.
According to Chrono Cross, as well as evolutionary theory, life rose originally in Earth's oceans,and the Greek letter nu is often taken in old writing to represent water. It is also the symbol forwave velocity in the mathematical formula for frequency. Interestingly, Spekkio appears as a red Nuonce the player reaches Level 99, implying the Nu's nearly supreme power, and in turn the power ofthe planet's will; in that form, Spekkio is nearly as difficult as Lavos to defeat, with 20000 HP --as much as the first and second forms of Lavos put together, and fully two-thirds as tough as thebeast's outrageously durable final mutation in Chrono Trigger.
Nus are always trying to find a place to sleep, are known to come out during periods of heavy rainand can be found in all time periods.
65,000,000 B.C.: Nus are found in the hunting range when all the other animals flee duringthe rain. Additionally, a single Nu can be found in the gathering place toward the end of the game;this one will change your party members' names.
12,000 B.C.: Nus are "servants" to the Enlightened Ones in the Kingdom of Zeal. More Nus arefound in this era than in any other. As alluded to earlier, they are almost always sleeping.
600 A.D.: Nus can be found hiding in the bushes of the Cursed Woods every now and then. Thesepoor creatures are constantly being harassed by the T'poles and Gnashers who will not let them sleepin peace.
1000 A.D.: A Nu appears when you open the Forest Ruins. He disappears shortlyafterwards.
2300 A.D.: A single Nu is seen in the Keeper's Dome, being programmed by Belthasar. Afterhelping Chrono's party obtain the Epoch, the game gives a message saying "This creature sleepsbeyond the flow of time."
The End of Time: The final form of Spekkio (the magic trainer) is a red Nu. The Red Nu isquite possibly the most deadly enemy in the game, as it has 20,000 HP, very high magic defense, anduses of all the game's ultimate techs. To fight this form, at least one character in the player'sparty must be at level 99.
Nus carry a weapon called the "Mop", which Chrono can equip and is even weaker than Crono's startingweapon. Nus award a whopping 30 tech points in combat, and have both an attack which can bring aplayer to 1 HP instantly and an attack that does only 1 HP of total damage (neither one of which candefeat the player on its own, but both together they can be deadly).
"All life begins with Nu and ends with Nu. This is the truth! This is my belief! ... at least fornow." - From 'The Mystery of Life' by Belthasar, Guru of Reason