The Arrival tablet

From Tardis Wiki, the free Doctor Who reference

A tablet was on the wall of Room M17 of Coal Hill Academy. It prophesied the Arrival, depicting an apocalyptic scene of a giant Weeping Angel casting down destruction on 21st century London.

The tablet was fragmented, with a specific piece missing from where the Angel's head should have been. It was assembled within a border of illegible inscriptions. (TV: The Lost)