Zaha Hadid’s spiky extension to the Serpentine’s new Sackler Gallery is futuristically (and characteristically) eye-grabbing. Yet, in the main galleries (which occupy a Grade II*-listed former gunpowder store), you’ll discover a more introspective atmosphere, courtesy of young Argentinian artist Villar Rojas. There's a giant clay jumbo wedged beneath a beam but the most incredible part of this show is contained within thick clay walls. Here lies a kind of workshop, lab and archive comprising some 2,000 objects. Made up of organic and sculpted elements, these strange items include bone-like growths made from clay, an air plant ‘growing’ in a beaten-up trainer and worn bars of soap arranged on a pedestal like a modernist sculpture from the 1950s. It feels like you've discovered an ancient tomb, with some objects decaying while others sprout decadently (and a little worryingly) to life.