The team used a 3D sand–hydrogel scaffold that they inoculated with Synechococcus sp. PCC 7002 (Synechococcus) — a photosynthetic cyanobacterium that converts CO2 to sugars during photosynthesis. Cyanobacteria are well known to survive extreme environmental conditions, including high and low temperature, salinity, and humidity, making them ideal candidates for living materials. These new materials are also capable of being regenerated from one parent “brick” using temperature and humidity switches. This corresponds to cycles of incubation at 37 °C, followed by low-temperature storage, where the gelatin matrix solidifies and encapsulates the bacteria. Splitting one brick in half and extending its shape...