On its back, two strips of soft-touch plastic break the back into segments: a removable bit up top that houses the 3.5mm headphone jack, a micro-SIM, a vacant microSD slot (the phone comes with 16GB of internal storage) and a fixed piece at the bottom, above which you'll find the Xperia logo.
It's not really designed for data storage -- instead, it's meant to be used as a certified Windows To Go fixed drive, "a fully manageable corporate Windows 8 workspace on a specially configured, bootable USB drive".