Researchers have made a lighter and potentially cheaper kind of shape-memory alloy.

The porous foam, made from a nickel-manganese-gallium alloy, stretches slightly when exposed to a magnetic field. It retains its new form when the field is turned off, but it goes back to its original shape when the field is rotated 90 degrees.

It responds faster than most shape-memory alloys (which react to temperature) and can be remotely changed, allowing for biomedical uses.