An Oak Tree by Michael Craig Martin?

An Oak Tree is NOT a famous painting. It is simply a glass of water 3/4 full which the artist Michael Craig Martin claims to have turned into an oak tree. According to him, it is not a glass of water any more, but it really is an oak tree. Of course he has achieved this without altering any of the original physical form of the glass of water. However, as one normally looks for evidence of physical change in terms of altered form, no such proof exists. Although en-route to Australia, he was stopped at customs, resulting in the artist having to admit it really was just a glass of water! A brilliant work.