Is it a weapon? Is it a tool? Is it a form of protest? Can it make your city pretty? Then it must be a seed ball!

Screening criteria for use: are you able to throw, drop, give to someone else to throw or otherwise deposit a small seed ball onto a patch of urban ugliness? Congratulations, you're approved.

A Japanese pioneer in "natural farming" developed the seed ball, a technique for planting seeds in abandoned places and often inhospitable land, says NPR. And anyone can make one and join in the fun.

Mix some mulch and a seed mixture, one that is native to the area and can withstand drought, and kneed it into a red terra-cotta clay. (It's important to use the red terra-cotta, according to the article, because other kinds have different chemicals that can affect growth.) Roll the mixture into balls and dry them. Find a blighted area, abandoned lot, your mean neighbor's driveway, what have you, and throw to your heart's content. 

The mud and clay protect the seeds from birds while the ball breaks down over three to five rain showers. The seeds germinate, and you end up with a lovely area where previously there was not.

Check out NPR for additional photos like the one above and more information.