Heart of the Land

A Heart of the Land (大地の心臓, Daichi no Shinzou), also known as Heart of Gaea''', it's a crystalline structure that continuously emits Dynamic D-Waves (in other words, sings) to create and maintain the existence of a given object. As examples, we have entire continents, like Metafalica, and the entirety of the planet Ar Ciel.

It's also known by its scientific name, the Selfstabilizing Tesseractal Nuclear Loop (四次正角性中核環, Shiji Seikaku Chuukakukan), and it could be said that it's the next level after the Triangular Nuclear Loop, which serves as the Hearts of the Reyvateils.

The Hearts of the Land have generally the same shape, but their size is highly variable: hypothetically, at their max size, they could create a continent of a several thousand Stons (a several hundred KM) in size.

=Structure=

A Heart of the Land is fundamentally made from three parts:

Core
This is the Heart of the Land itself. It's usually located at the very center of the continent, and it's a plasmatic existence, given it doesn't have an actual form.

Core Glass
It's a crystal whose function is to protect the Core. Given that the Core doesn't have a physical form, and thus, wouldn't be able to exist in the world, it also has the function of storing the Core to allow its existence. When talking about a Heart of the Land, the Core and the Core Glass are referred to as if they were a single entity.

External Shell
This is a part that resembles multiple shells rotating upon each other, all having the core as their central pivot. Each one of these shells rotate independently from the others, covering any gaps and crevices that might exist within them, and are structured in a way that makes impossible to take out the Core from within them.

Its main role is protecting the Core from the outside world the outside, both from the physical impacts (D-Waves) and from the mental interferences (H-Waves), and also, prevent any damage from being done to the Core from the negative feelings that exist in the world. If the Core was removed from the Shell, it would be eroded by the influence of the negative feelings that fill the world, and before a long time, it would vanish completely. That is the main reason for the existence of the Shell, though also, because nothing can penetrate these multiple layers of rotating shells, nothing is able to extract the Core from within.

However, by conversing with the Heart through a Song, and demonstrating that you don't hold any hostile intentions towards it, you can be able to extract the Core from the Shell.

=Creation=

So far, the only method known for creating a Heart of the Land is using the song of creation, Metafalica, but given that this method also extracts the Triangular Nuclear Loop or LEM of the singer, or any Reyvateil near her, and ends killing them, it has never been put into use.

It's also possible to extract a piece of the Core using a song, which will in turn create a new and independant Heart of the Land. However, the new Heart will be empty and unuseable, and will have to be filled with feelings from a great number of people before it can accomplish its functions.