Meaningless offer

When I encountered this empty aquarium (or similar-sized glass box) on a street-corner, there was no heat pad visible. The note was accompanied only by two dead branches or root stumps. Were the branches used to anchor the heat pad, which had since been removed (as per offer)? Or had some trickster replaced the heat pad with dead branches? Or had the note been dropped in from elsewhere? Yet another street-side mystery to which we’ll never have the solution…