this type of structure is found in nalanda complex that are still excavated .i found greek bricks there.
Seen near Shiva (Varaha) temple.
Seen near sri Kodandarama temple.
Sun in sun temple.
These are seen at Anegondi.
Bhima with Sougandhika flower, seen in Bhima's Gate.
Seen near water pavilion.
It is called as Badavi linga (poor ladie's linga)
If you move through the Turth Canal, near Veerabhadra temple, after 2 to 3 kilometers of journey you will find this beautiful lonely Ganesha.