Fittonia are small spreading plants grown for leaves laced with white, pink or red veins. They stay under about 15cm (6in) tall, which makes them a common choice for terrariums.
The fainting
A thirsty Fittonia collapses completely, going limp and flat as though it has died. Water it and it stands back up within a couple of hours.
It is dramatic and reversible, but not something to rely on. Each collapse costs the plant, and repeated ones cause leaf loss.
What every Fittonia wants
Humidity above 50%, and preferably higher. This is the whole difficulty with them, and it is why they do so well in a closed terrarium and struggle on an open shelf.
Medium indirect light, and soil kept lightly moist at all times.
Fittonia are non-toxic to cats and dogs.