The symbol of anahata chakra

The 12 petals of the lotus, each has a Sanskrit symbol, surround two triangles superimposed on each other forming a hexagonal star. 

The upward-pointing triangle represents Shiva (yang) and three higher chakras (anahata, vishuddha, and ajna) and the downward-pointing triangle, represents Shakti (yin) and the three lower chakras (muladhara, svadhistana and manipura). They also indicate inhalation and exhalation. 
A symbol of perfect balance, it is traditionally colored smoky gray, like incense rising in a draft of air. In the center is a bana linga like a crescent moon, to represent the psychic blockage within. It is set in a shinny golden triangle - showing the explosion of the divine light that can be seen when the vishnu granthi (knot) is untied and the heart chakra opens.
The deer at the bottom refers to the lightness of physical substance in the air element.

There are also the picture of two Deities: Isa and Kakini

Isa is an aspect of Shiva, Lord of Speech. Depicted as shinning white, or brick red, this deity has three eyes and two arms. He makes the gesture of dispelling fears with one hand while giving blessings with the other. When we meditate on Isa we become like him, able to "protect and destroy the world" at the same time.

The goddess Kakini is shinning yellow in color. She carries a noose reminding us not to get caught up in spiritual expectation - which, like trying to watch a pot boil, is sure to delay progress. The skull she holds tells us to maintain a pure mind. Her two other hands make the same gestures as Isa, dispelling fears (palms up) and giving blessings (palm up).

Namaste :-)

Studies based on the book "Chakra Workout" from Mary Horsley. Published in 2007 by Sterling Publishing Co., Inc.