What's the identity of the fungi/mold in my garden?

Today I found something had grown on a log in my garden but I don't know what it is. It's a round blob, about three inches wide and two tall. It's attached right onto the end of the upright log (no stem) It has a white silvery skin which is easy to break and and inside is a squishy brown substance that seems constant all the way through with the consistency of clay. Not a clue what it is, enlighten me?