[Lew]

Not sure Gav when I googled Indian bull this pic showed up but I think the pic was taken here in the states. Here are a few more pics the top one is Shiva riding a top of one also notice the center photo of the side view of the bulls head it's ear has a similar shape to the ear of the dagger hilt. Here is some more research tidbits.

Shiva's guardian is Nandi (the white bull), whose statue can often be seen watching over the main shrine. The bull is said to embody sexual energy, fertility. Riding on its back, Shiva is in control of these impulses.

He often holds a trident, which represents the Hindu trinity of Brahma, Shiva and Vishnu. It is also said to represent the threefold qualities of nature: creation, preservation and destruction, although preservation is usually attributed to Vishnu.