That's F for Flower. A PVA water soluble weapon of mass foliation. Otherwise known as a Seed Bomb deployed by ninja gardeners to sew seeds in hard to reach places. See Also: http://www.guerrillagardening.org/ggseedbombs.html

Sure, there are cheaper and more efficient ways to do this... but... pfft... The idea is to stuff it with some compost and seeds and then throw it somewhere that you think could use some color, but you either can't get to it or it's where people wouldn't appreciate seeing you digging around. Then wait for mother nature to dissolve the shell and make some magic.

This of course requires water soluble PVA http://www.makerbot.com/blog/2011/02/21/makerbot-introduces-water-soluble-3d-printer-filament/ since you don't want to wait a thousand years for ABS to go away. I'm not even sure this will work, however PVA is supposedly bio-degradable http://www.eliteanglingproducts.com/PVAEnvironment.asp and is used as a seed coating http://www.celvol.com/sekisui/sek_seed-coating.htm so hopefully it's safe. However, I will assume it's not safe, I'm stupid, and advise you not to do this. Also, I am not responsible if you get arrested for defacing someone's private property with beautiful flowers. :)

However, I'm going to test it anyway (did I mention I'm an idiot and you shouldn't do this?). Unfortunately it's not the best time of the year to try it, but I loaded one and sat it in a pot outside. I also sat one in a pot indoors that I'll run some water over whenever I water my other plants to see how it dissolves naturally over time and if anything grows out of it. I also threw some of the seeds into another pot just in case these old seeds are no good and to compare the growth. SCIENCE!

Alternatively, you could print this in something other than PVA and just use it like a little box to store things in...