no.. it wun grow mouldy or is it prone to fungus attacks.
the most you can gather from storing in the dry box is to delay the shiny contacts from turning dull, which is inevitable. Other than that.. there's no need to store it inside. I'm a testament, i've used my external 2.5" drive for more than a year. It's never stepped foot into the drybox for even 1 sec. It still works like a charm with dull contacts.