Who created Vishnu, Siva and Brahmma?

I am a staunch vaishnavite. However, some odd mythological references here and there in the web or in offline magazines that might be in total contrast to my beliefs don't make me angry.

In fact, I am amused when I read such tidbits.

Here is a sample.

Before the beginning of time, there existed a Goddess named Ammavaru. She laid an egg and from it, the triumvirate Brahmma, Vishnu and Siva came out.

Look, I have not created this myth; it is available in the web.

Here is the source:

"Ammavaru."

I dug deep and learnt that the South Indians worshiped Ammavaru in a symbolic way. They filled a metal pot with rice, placed a painted coconut on top of the rice and the pot was covered with a saree.

The image of Ammavaru found in wikipedia.