Many a times we've heard the words "rock solid" used to describe the build quality of a technological product. Seldom does that actual term fit literally, however.
But in the case of some new flash drives a design house has been working on, the meaning can be used quite literally here.
Yes, what you are seeing is a flash drive module enclosed in a block of cement with the capacity of the memory inside being engraved on it (it's been demonstrated in sizes of 64, 128 and 256GB). The weight (in grams) of the drives also match their respective capacities.
The performance/type of flash memory used inside is anyone's guess. We only know it sticks to the usual USB 2.0 interface. As for the chances of these hitting mass market? Not very likely. But you have to admit; very cool!