This is a fragment of a Roman imbrex, which were semi-cylindrical tiles that overlapped the edges of flat tegulae roof tiles to help keep buildings watertight. The tile bears the impression of a leaf, which must have fallen on to the tile whilst it was still wet. This is an uncommon but unsurprising find, as freshly made tiles would have been dried outdoors, perhaps under only basic cover. Unfortunately, the impression is not sufficiently complete to identify the species of the leaf.