First, let’s go through the different centres called the chakras.
So, the first chakra at the bottom of the spine is called the Mooladhara and it is represented by a triangle with its apex down and the colour associated with it is yellow, the colour of the earth, and the triangle is placed in the middle of a square, a yellow square which again represents Prakriti or the material earth, the solid earth meaning energy at its grossest level of vibration.
The centre or Padma–chakras are also called padmas because they are like a lotus, which means just as the lotus blooms, the centre also blooms when the Kundalini energy touches them. So, they are also called padmas or lotuses.
So, the next lotus or the next chakra is called the Swadisthana chakra and it falls between the Mooladhara, which is the lowest and the Manipura chakra at the navel. The colour of Swadisthana is silvery like the moon, like moonlight and its symbol is a crescent moon.
Now, you’ll find this crescent moon on Goddess Durga’s head, and also on Lord Shiva‘s head touching his locks. It is the great tantric symbol of the astral world and subtle worlds, and its Tattwa is the principle of ‘aapas‘ or the principle of water.
Now the first chakra, the Mooladhara, represents Prakriti or the solid earth or solidity, and the next one we discussed, the Swadisthana, which is silvery and is shaped or symbolised by the crescent moon, represents the watery tattwa or the aapa tattwa, also called the ‘tejasa‘ or the dream tattwa. This is so because the energy called the Kundalini is ascending from the gross to the subtle–from solid state to the liquid state.
From solid to liquid to gaseous, the energy becomes subtler and subtler and the consciousness moves from gross to the subtle.