I put a lot of thought into that problem:

So a baby, a seed, any living thing (or even a chunk of something that was once living I suppose) is more complex, which I why I went with 'machine' to exclude those.

I also toyed with saying 'own' rather than 'held', but a modern electric car is basically a beefed up phone with a bunch of driving stuff too, so they wouldn't pass that test.

There are some edge cases: someone upthread held a classic inertial guidance system, and a modern GPU is arguably more intricate, though much more single-function, and good luck getting your hands on one of those anyway!