need some help with a certain device .. dont know the name

[Asterix]

while I was at the army they've put some kind of glowing color on the walls and the floor which was invisible during the day and showed you the way at night.
doesn't need energy, you can't turn it off and it only needs sunlight during the day

//Edit: found it

http://www.aliexpress.com/item/photo...912448808.html