There are several other qualities that make their model stand out, too. At a glance, it just looks different: its flattened, white, 3D-printed casing stands in stark contrast with the cylindrical, metal sensors of the other four teams. It’s also the only sensor with a clear answer to one of the most frustrating problems with oceanographic instruments: biofouling. Anything that gets put in the ocean becomes habitat for a diversity of critters from barnacles to sponges that can damage instruments and are costly to remove. The pHenom is built from a special plastic that resists the attachment of marine organisms. But most importantly, it’s by far the cheapest to make. The team estimated that it would cost was about $1,000—a tenth or less of the price of other models in the finals. The price, low-maintenance housing, and ease of use make it a strong contender for the affordability purse.