The creature was known as the “Watcher in the Water”. It probably wasn't there when dwarves actually lived in Moria. Some time after that, the gate-stream Sirannon was dammed (probably by the Watcher).
The Watcher in the Water was a horrifying and mysterious creature with many tentacles that lurked within a dark stagnant pool or lake beneath the western Walls of Moria, which was created by the damming of the Sirannon river.
What is the creature outside of the Mines of Moria?
Durin's Bane. This Balrog appears in The Lord of the Rings, encountered by the Fellowship of the Ring in the Mines of Moria. It survived the defeat of Morgoth in the War of Wrath, escaping to hide beneath the Misty Mountains.
They are older than he." Based on those two Gandalf quotes, it's safe to theorize that the Watcher in the Water was one of the Nameless Things. However, exactly what the Nameless Things were is still a mystery. Some fans think that Morgoth created them in the pits of Utumno.
Far below even the deepest mines of the Dwarves lay a primordial underworld of tunnels, streams and lakes in perpetual darkness, inhabited by primitive creatures.
The Watcher in the Water & the Nameless Things of Moria | Tolkien Explained
Who woke the Balrog in Moria?
For more than five millennia, the Balrog hibernated in his deep hiding place at the roots of the mountains in Khazad-dûm. He remained undisturbed throughout the Second Age and most of the Third, before the mithril-miners of dwarf-King Durin VI awoke him in T.A. 1980.
In the end Tolkien stated that there were probably "at most" seven Balrogs: In the margin my father wrote: 'There should not be supposed more than say 3 or at most 7 ever existed. '
This pale-green, luminous and many-tentacled creature may have been a nameless thing as it was stated to be among the "older and fouler things than Orcs", dwelling within the "deep places of the world". Gandalf speculated that the Watcher was drawn out from a dark lake beneath the Misty Mountains.
Gimli didn't know about Moria's fate because there had been no communication between Erebor and Moria for 25 years, and the Dwarves were hopeful and did not want to accept failure until there was certain news.
Gandalf's main reason for supporting Thorin's quest in The Hobbit was to eliminate the threat of the dragon Smaug, who would be a powerful ally for Sauron. Despite popular belief, the Balrog known as Durin's Bane was more powerful than Smaug in Middle-earth, being a literal, primordial demon.
The only recorded instances of Balrogs having been slain are Gandalf's slay of Durin's Bane, Echtelion's slay of Gothmog and Glorfindel's slay of an unnamed Balrog.
The movies skipped the prelude in favor of the main event: Gandalf standing on the Bridge of Khazad-dûm, holding the Balrog off before shattering the bridge beneath its feet and sending it plunging into the abyss beneath.
Gandalf's occasionally mean attitude towards Pippin is rooted in factors such as the stakes of their mission, Gandalf's protective instincts towards hobbits, and his desire to mentor Pippin, offer him guidance, and see him grow.
From TA 2989 to TA 2994, the re-colonization of Moria was an attempted expedition led by Balin to re-take the ancient Dwarven Kingdom of Khazad-dûm. An initial effort was successful in reclaiming some of Moria from the Orcs.
Though Gimli has no children, he is not the last Dwarf of Middle-earth. After the fall of Sauron, his people continued to thrive in the Lonely Mountain. Gimli made his home in Rohan, in the Glittering Caves of Aglarond, and many of his kinsfolk came with him.
Unfortunately, the Fellowship's journey only confirmed what he had feared. Although Gimli knew that Moria could be dangerous in the book, he did not know about Balin's death in The Lord of the Rings: The Fellowship of the Ring movie possibly due to slow communication and Dwarves' perception of time.
Therefore, the only explanation as to why Gandalf doesn't reveal the Balrog's presence to the others earlier in the films, is that it is a plot device used by the writers and the creative team in order to increase the dramatic tension of Frodo's decision.
Gandalf didn't know that the Mines of Moria had fallen. He mentions he had been through Moria before, but it was before it had been resettled, which means it would not have had the chance to be overrun yet. All that was known about the mines was that the dwarves had gone silent.
Other Tolkien scholars, in turn, simply believe that Tom is one of the Nameless Things that inhabited the depths of world since Ainulindalë. Although it was thought by some that Bombadil would be Eru Ilúvatar himself due to Goldberry's statement saying "He is.", J.R.R.
Thus, Galadriel's dark form in Jackson's The Lord of the Rings personified what would have occurred had the Lady of Lothlorien given in to temptation and taken the One Ring for herself. She would have succumbed to evil because the Ring was indomitable, even with her power.
Secondly, Balrogs were the epitome of malice and power while Sauron only ever won one of three fights he ever had. Sauron was the great deceiver. His power lies in planning, subterfuge, manipulation, and corruption. Strength wasn't his game.
