lava lamp 
noun
A transparent electric lamp containing a viscous liquid in which a brightly coloured waxy substance is suspended, rising and falling in irregular and constantly changing shapes.Only a lava lamp illuminated my cramped, dark apartment, its red-tinted light bouncing off the red of the walls....
- I know it's a proper album, because my favourite songs keep shifting and changing and rising and falling, like wax in a lava lamp.
- Ariana squinted as she tried to make out the figure in the pale red light of the lava lamp.