A finial finishes off the roof and may be pointed or round and sometimes is ornately decorated. Our finial is round and plain and we've never thought twice about it.
Martin has been filling the gap between the roof and pigeonnier where, when it rains hard from the east, it leaks down onto the veranda. He knows old buildings and tells us things about our house. Things we hardly notice suddenly become special. Like our finial. He showed us it's an upturned hand-made cooking pot, with the handle still intact. Not many finials like that!