Spiral reliefs resembling those at Tarxien once adorned the Ġgantija temples, but have faded to a level where they are only clearly recognisable in a series of drawings made by the artist Charles de Brochtorff in 1829, immediately after the temples' excavation. The Tarxien phase is characterised by a rich variety of pottery forms and decorative techniques. Most shapes tend to be angular, with almost no handles or lugs. The clay tends to be well prepared and fired very hard, while the surface of the scratched ware is also highly polished. This scratched decoration remains standard, but it becomes more elaborate and elegant, the most popular motif being a kind of volute.