Earth Heart Chakra
When you do the grounding meditation, you connect with the fiery crystal in the center of the Earth. It is the source of Shakti for us as humans living on this planet, and the heart of Gaia. It is a manifestation of the Mother Goddess, a heart and a womb. When we arrive as souls on this planet, we go to the center before incarnating into a body. Here we get initiated and adjusted for living on this planet. The Earth Heart meditation offers instructions for returning there, when you need healing or comfort. It is a really, really lovely experience.
The center of the Earth is a chakra that is shared by all life on this planet. Some chakras, like the main 7 are personal, but there are also group and universal chakras. What is given to Goddess, comes back better, multiplied. So, in the grounding, sending energy to the center, gives a multiplied return.
Symbolically, the layers of the Earth between your feet and the crystal, is the underworld. The place of the dead, and where the archetypes and various denizens of the collective consciousness live. Depending on your paradigms, wandering in the underworld might bring you face to face with the Hell of Dante or the fields of the dead of greek mythology, or all sorts of other critters and beings whom you would probably prefer not to meet. If you want to meet them, stay in your body and do the mirror meditation, instead.
The Earth heart crystal is also the home of the planetary Akashic records. Many people make a big deal out of reading the Akashic records; I suggest you avoid it, don't bother.
What is often not realized, is that the Akashic records do not only contain the records of everything that has ever happened on this planet- they also contain all infinite possibilities of everything that ever can or could happen on this planet.
In an infinite universe, anything that can exist, does exist, somewhere, somewhen. Whether it exists for us in this timeline and dimension, is another thing altogether.
If you read some people's channeling of the Akashic records, you may notice a lot of wild stories! Because of the nature of perception, when you read the Akashic records you will only see yourself reflected. What will come up, is a reflection of your own hopes and fears... not the truth of what Is.
Suffice to say, you can end up getting really confused!