It is the depiction of story Samudra Manthan where the Devas and the Danavas took part in a tug of war contest to churn the elixir from the oceanbed to attain immortality. The process of churning the ocean also released a poison called “Halahala” that could wipe out the whole of creation. Lord Shiva consumed the poison himself to save humanity from calamity and destruction. In the process, Shiva’s throat turned blue because of the pain and intensity of the poison.
The story of Samudra Manthan also has a hidden message, the act of helping others in the time of need, in spite of going through a lot of pain and suffering to do good for humanity.