OK, so it's kind of a sticky, partially inflated soccer ball.
The Blob Bot is defined as a "chemical robot" (we're mildly offended that they'd use the R word so liberally here), and it moves thanks to a process called "jamming," basically filling its empty areas with air and letting it out as necessary to control the shape. You can watch it in action here:
Yes, military technology has advanced to a point where we have been able to replicate the flopping movements of a dying fish. Granted, the Blob Bot is still very early in development, but when it's finished, its DARPA-sponsored creators hope it will be able to"squeeze through tiny cracks in pursuit of its target" and then ... spy on it with tiny cameras? Explode into a mass of goo? Sneak into sandwiches and hope its target chokes on it? We don't really know, because they never say what exactly their goal here is. All we know is it sounds creepy as hell.
Build weapons first, ask questions later.