Exhibited at the BSA Space as part of the Boston Design Biennial in 2013, Matter Design's Helix is a concrete spiral staircase that is full of surprises. Chief among these is its size - the stair was built at half-size to address the practical issues of weight, liability and access - but more important are the details of its assembly. While the steps of most spiral staircases are supported from either the stair's perimeter or a central column, Helix transfers loads directly through the steps below to its base which, rather than resting on the floor as it appears, is in fact suspended from a beam in the ceiling.