It's actually based on those directional creature things in Asian mythology - Black Tortoise, Vermillion Bird, White Tiger, Azure Dragon, Yellow Dragon, etc.
Oh, that Danny Phantom episode I based this part on was "Girls Night Out".
CHAPTER FIVE:
Fallen and Shattered
"Okay . . . how do we beat that thing?" Gaz asked.
"Hope we get lucky?" Horse replied brightly.
"Anyone else?"
But Sakki had charged forward and attempted to punch and kick and basically melee-attack it, but it would not penetrate the shell. She backed off as it knicked her metallic body.*
"Well, that beak mouth of it is sure sharp," Sakki said, with false bravado.
"I think we need to aim for the shell. Penetrate that first, then we can consider what to do next." Aila said.
Faerie attempted to get through the shell with that huge honkin' battleaxe of hers. But it didn't even make the smallest nick. Faerie looked to be offended by this turtles superior defensive abilities.
"Well!" she said.
The RAFgirls were debating and deliberating on another means of attacking the turtle, each of which failed or were incredibly unlikely to work. Shadow, however, was gazing around, taking in the turtle and the semi-transparent green stone. She had a startling notion.
"The guardian isn't important," Shadow said suddenly.
"The what?" Ash asked, as the RAFgirls broke off the debate.
"The turtle is guarding that gem. We don't need to destroy that turtle. We need to shatter the stone."
"Good idea!" Faerie declared. "Any idea how?"
"Nope."
"Swell."
But the turtle wouldn't let them anywhere near it. Shadow got so frustrated, that she used the earth element to lift the turtle's legs on earthen columns, the left side being much higher than the right. The left side was continuing to be higher, until the turtle tumbled off, landing on its back. Unable to right itself.
"There! Now, stay there, you black-shelled . . . uh, ragamuffin!"
"'Ragamuffin'?" Alic asked, teasingly.
"Okay, so my battle banter needs work." Shadow sniped. "Just destroy that stone."
<But HOW?> Noelle asked.
"Perhaps simultaneous energy blasts?" Aila asked.
"But Shadow is the only one here with energy blasts.**" Gaz pointed out.
<Wait -- what if we use the Mark?> ND said.
"The Mark . . ." Horse said, looking at her flipper.
"We've got nothing to lose," Dameg said, and she aimed her mark at the stone. The rest of the RAFgirls did the same. Shadow did nothing, as she did not carry the Mark.
The stone seemed impervious to it at first. Then it fissured, then fractured. After several tense moments, it shattered into powder, into dust. It was gone, and seconds later, there was a green flash. And the RAFgirls dashed back to RAF as the large turtle petrified, then dissolved into dirt.
---
*Yes, Sakki is a VOLCAROID in this, which I noticed that she changed on the Registry.
**If I'm mistaken, sorry!