This is Vadiraja, a philosopher and saint belonging to the Madhva sect of Hinduism. Vadiraja is closely associated with Udupi (a coastal city in Karnataka), Sode Mutt and the rotational worship at Krishna Mutt. Vadiraja is a historical figure and his birth year is recorded as 1481 of the common era. Vadiraja is known for his literary work and more than one hundred works have been credited to him.
Here he is sitting in Ardhapadmasana on a turtle, wearing Tulsimani mala and holding staff on his right hand. Incidentally, the staff signifies that the person is the protector and propagator of Vedas. Vadiraja’s right hand is touching his chest and his left hand is in Varada mudra.
The vertical religious mark, namam, and his sitting on a turtle identify this idol belonging to the Vaishnava sect. The staff on his right hand and the Kamanadala (water container) on his left identify this idol as that of a saint.
It is the cobra protecting his staff that identifies this icon as Vadiraja.
The idol is about 6 cm in height and probably dates to the early part of the twentieth century. It is most likely this icon is from Karnataka, India.
9 June 2019: Corrected the name of the Mala Vadiraja is wearing to Tulsimani mala. Thanks to Rashmi, a Twitterti.