It turns out that when you make an unconventional phone that lets you swap out its core components, it can be hard to make that same phone stay put together — at least compared to today's smartphones. Google's Project Ara team has tweeted an explanation for why its pilot test plans were reworked and delayed: the current model wasn't faring well when dropped. "No more electropermanent magnets," the team tweeted.

That poses a challenge since Google now fundamentally needs to rethink and rework how Project Ara's modules join together. And this time, that mechanism needs to survive typical falls (or at least match the durability of your everyday mobile phone).

We are testing a signature experience to attach/detach modules. #ProjectAra #HopeYouLikeIt — Project Ara (@ProjectAra) August 19, 2015

Project Ara's creators now say they're "testing a signature experience" to attach its modules. We're not exactly sure what that means, but we imagine after the slight black eye of having to push back Ara's debut, the team will be eager to demonstrate its revised design almost as soon as it's ready.