As someone who works on the written documents of the ancient Aegean and Cyprus, I come across clay tablets a lot. Clay was a very useful medium for writing in the ancient world because it was quite easily available and could be formed into different shapes, and all you need in order to write on it is a stick. Luckily for us, a clay tablet also has a good chance of surviving for thousands of years provided it has been baked.
A while ago I posted a picture of one of my favourite clay tablets on Twitter, a Linear B document that we label PY Ep 704 (which is code for saying that it comes from Pylos and deals with landholdings). (Photo courtesy of Silvia Ferrara.)