This story is from the Mudgala Purana. Gana or Guna or Ganasura was the son of king Abhijit and his wife Gunavati. A strong, but greedy and hot-headed warrior king, Gana pleased Shiva with his worship. Shiva granted Gana the kingship of the three worlds – heaven, earth and underworld and decreed that Gana could not be killed by anything that possessed any of the three gunas. Once, Gana and his entire army arrived at the hermitage of the sage Kapila, who owned the wish-granting jewel Chintamani. 

Kapila served the prince and his army delicious food created with the help of the jewel. The greedy prince desired to acquire the jewel, however the sage refused. Gana seized it from the sage. Kapila, a devotee of Ganesh, prayed to Ganesh to retrieve the gem. Ganesh appeared with his army in Gana's dream; one of his soldiers cut Gana's head. Gana woke up and marched towards Kapila's hermitage with his army, intending to slay the sage. Abhijit tried to dissuade his son and advised him to return Chintamani to the sage, but in vain. Gana started to destroy the hermitage.

Ganesh’s shakti (‘power’) – the goddess Siddhi appeared and created a thousand-armed warrior Laksha, who destroyed Gana's army while Ganesh himself beheaded the arrogant prince. Ganesh returned the jewel to Kapila. However, the sage chose to have his Lord instead of the jewel. Thus, Ganesh stayed on in Theur with Kapila, taking the name of the jewel Chintamani. 
The name Theur originates from the Sanskrit word ‘sthavar’ meaning stable. According to another legend, the god Brahma meditated here, and his restless mind became ‘sthavar’ due to Ganesh's blessings. Since Ganesh got rid of Brahma's Chintas (worries), he became known as Chintamani. According to yet another tale, Indra worshipped Ganesh here under the Kadamba tree to get rid of the sage Gautama's curse. The place was thus known as Kadamaba Nagar, the town of the Kadamba trees.
At the temple, the deity faces east and is smeared with Sindur, and its trunk is on the left side. The eyes are studded with rubies and precious stones.
 

Sevas and pujas: Kartik Vadha Ashtamni: Rama Madhav Punyotsav is celebrated.

It is believed that once, Brahma was restless and wanted to end his life. He sought help by meditating on Lord Ganesha in Theur, hence this temple is called Chintamani. The face of the deity is towards the east and the trunk is towards the left, which is self-proclaimed. His eyes are studded with rubies and precious stones.