Full Idea
There are plenty of examples to show that ordinary proper names simply are not rigid designators.
Gist of Idea
Examples show that ordinary proper names are not rigid designators
Source
Michael Jubien (Possibility [2009], 5.1)
Book Reference
Jubien,Michael: 'Possibility' [OUP 2009], p.127
A Reaction
His examples are the planet Venus and the dust of which it is formed, and a statue made of clay. In other words, for some objects, perhaps under certain descriptions (e.g. functional ones), the baptised matter can change. Rigidity is an extra topping.