Namibia's desert ecosystems might look ageless and unchanging from a distance, but surprisingly small actions can make a real difference in an ecosystem where every drop of water counts. A recent study revealed that Hartmann's mountain zebra make subtle, yet measurable, changes to the environment just by rolling in the dust. Since none of Namibia's other desert-adapted mammals enjoy a good roll quite like zebras do, this particular role in the ecosystem as unique as their stripy coat.