Bapuji Bua is a popular local deity in Maharashtra. There are many temples of this god in many villages.
The idol of Bapuji Bua does not have a definite shape like other Hindu gods have. His idol is a round or an arbitrarily shaped stone. This stone is covered in orange-colored lead oxide, and two artificial human-like eyes are stuck on it. In some temples, a silver mask of a male with a mustache is fitted over the idol.
When I started to research about him, I could not find much information on the Internet. There is a legend of why and how the worship of Bapuji Bua started.
The Legend of Bapuji Bua:
On one day while meditating, Lord Shiva found that his devotees were in difficulties and agonies. Therefore, to give them relief, he appeared in the form of a solid stone in a corral in Kadape village. This stone came out of the ground and was firm at the base. The corral belonged to a person name Bapu Gawali who was a milkman.
As usual, when he went to his farm, he found a stone popped up from the ground that was not there previously. He tried to push it, and to his surprise, it started bleeding!
Thus, worried and flabbergasted from the incident, he went to his home and slept that night. In the early morning, he had a dream in which he saw Lord Shiva, who told him that he had appeared in the corral and would stay there permanently to help his devotees.
Bapu Gawali was very happy with this dream, and he told this to his wife. Then they went to the corral and did Puja and offered a prayer to the stone. When villagers of Kadape came to know about this incident, they also joined them. They decided to name this form of Lord Shiva as Bapuji Bua that was the name of the person who first found it.
This story is particularly related to the Bapuji Bua temple in Kadape, which is one of the most popular temples of Bapuji Bua in Maharashtra.
But upon further research, I found that there are different beliefs among people about Bapuji Bua in different villages. For some Hindus, Bapuji Bua is not a form of Lord Shiva but is one of their ancestors. Therefore, the worship of him may also be a form of ancestral worship.
It is not known why the name Bapuji Bua was given to their ancestors, and how did the villagers from different villages end up giving the same name to their ancestors. As far as I know, this deity has been worshipped for hundreds of years.
The word Bapu is a term of respectful compellation for a male. It also means father. It seems to be originated from the word Baap that means father in Marathi and other Indian languages.
The word bua is used for male sadhus in Marathi. It is also used for adult males.
Therefore, the words Bapuji Bua mean a respectable male person who might possess some divine powers.
In the Konkan region of Maharashtra, he is called Bapdev that translates to “father god”.
It is possible that people from one village might have started calling their ancestor by the name of Bapuji Bua, and people from other villages copied it. Thus, it spread all over Maharashtra.
Therefore, we can say that Bapuji Bua is either a form of Lord Shiva or the name given to the ancestors.
This topic requires further research. If you have more information about this god, please use the comment section to inform us.
Reference: http://kadapesansthan.com/history/
Image Source: https://www.youtube.com/watch?v=y0Hv_r3C2MY