"Save the bees! Save the trees! Save the whales! Save the… snails!"

The Australians, as ever. They observed that the population of small marine animals in Sydney Harbour had thinned out because the shoreline had been encased in stone, scratched their heads, and made little houses for barnacles, molluscs and assorted underwater creatures.

The project is called Living Seawalls, and for several years now it's been actively helping restore the marine ecosystem in the city.

It's a collaboration with Reef Design Lab (extremely cool people, have a look at the site) and the Sydney Institute of Marine Science.

They designed the houses starting from "who likes living where," 3D-printed them, made moulds, cast them in concrete and bolted them to the walls. Over two years, a 30% increase in life — in places more than on ordinary rock.