Somaskanda is one of the most common forms of Siva. It is found only in South India and mostly in Tamil Nadu. Siva, Uma and their son, Skanda, are on the same pedestal (Bhadrapeetam). Skanda may be standing or seated or dancing. In the above example, he is missing. That explains the hole next to Siv’s left leg. Siva, right leg hanging down, and Uma, left leg hanging down, are seated comfortably (Sukhasana).
Siva is holding axe (tanka) and deer (mirga) in his upper hands. The lower hands are in Abhaya (protection) and kataka (holding something) mudra. Uma is resting her left hand on the pedestal whereas her right hand is in Kataka (Holding mudra).
Somaskanda is a must in every temple, as a processional image. It is one of the five main prescribed processional images. Some temples have stone sculptures of Somaskanda behind the main manifest form in the inner walls.
The above bronze is a scaled down version of processional image and appears to have been inspired by a Somaskanda group in Thanjavur Art Gallery (ref The Divine Bronzes, S Rathnasabapathy 1982, Page 99 Cat 33).
The width is about 19.5 cm and the height is 16 cm.