For a small, cold blooded creature living in the Saharan desert, like the sandfish do, the ability to quickly burrow into the sand is a useful trait. But the sandfish doesn't just burrow - it swims. The filthy rich Scrooge McDuck notoriously used is wealth to swim through rather than spending it, and how he did it is a mystery, but it probably has something to do with him being in a cartoon. The sandfish, though, is not a cartoon character, so how does it do it?
It was thought that the sandfish paddled through the sand with its legs. To find out, researchers at Georgia Institute of Technology watched "burrowing" sandfishes in a bead-filled glass container with a high-speed X-ray imaging system. Physicist and lead reasearcher Daniel Goldman tells LiveScience:
"When started above the surface, the animals dive into the sand within half a second. Once below the surface, they no longer use their limbs for propulsion - instead, they move forward by propagating a traveling wave down their bodies like a snake"
I don't think that's exactly how Scrooge does it, though, so researchers has plenty of work left to do.