“Back in the day,” people stashed all kinds of treasures in cigar boxes, including family photos, or used them as handy storage bins for sewing supplies or loose change. This cigar box was used for a different purpose. It held the first sample of Plutonium-239, first created in 1940 by a team led by Dr. Glenn Seaborg. Seaborg stored the sample in this box, after discovering its fission properties in March 1941.
Courtesy of the Creative Services Office, Lawrence Berkeley National Laboratory.
U.S. NRC Blog 
Well, I do believe he meant ‘convenient’. That said, it’s rumored rather strange things can happen in such places as ‘convents’…They fissioned their single god yielding alpha, beta, and ghost-like gamma, right?
1. Somebody in that scientific trio (or in their family) was a cigar smoker.
2. The cigars formerly inside were on sale, reduced from 10 cents, to 5 cents each.
3. The cigar boxes appear hand-made with dovetailed wooden joints which required some word-working expertise. Were the boxes cheaper to make than the total cost of cigars packed within?
For what it’s worth, the “non-fissile” Pu-240 and Pu-242 isotopes will still fission if hit with fast neutrons (over 1 MeV), and in fact have a greater fission cross-section than U-235 in that energy range. A fast-spectrum reactor will consume all plutonium more or less indiscriminately.
There’s no better way to make weapons-grade Pu unusable for weapons than to put it through a nuclear reactor. A large amount of what does not fission gets converted to isotopes which make the material useless for weapons. The MOX plant in N. Carolina, currently the subject of controversy, is intended to eliminate weapons material by exactly that means.
What a sample that Glen Seaborg, the Italian refugee scientist Segre’ and Glen’s assistant Joseph Kennedy precipitated, after pains taking meticulous amount of work, finally on March 28, 1940. This sample you see in that cigar box is the original platinum dish (measured two-thirds of an inch across and half in in depth) which contains the spec sample of 0.25 micro grams of Pu-239. It is preserved to date in that dish with a simple protective layer of Duco Cement glued to a piece of card board. None of the bloggers here would appreciate the importance of that discovery to those three at that time.
“Convent”? What would nuns want with plutonium?
=) thank you. (Aside: no more nuclear weapons should ever be built.)
Here is an excerpt from one of our Science 101 blog posts https://public-blog.nrc-gateway.gov/2014/05/15/nrc-science-101-what-is-plutonium/
The various isotopes of plutonium have been used in a number of applications. Plutonium-239 contains the highest quantities of fissile material, and is notably one of the primary fuels used in nuclear weapons. Plutonium-238 has more benign applications and has been used to power batteries for some heart pacemakers, as well as provide a long-lived heat source to power NASA space missions. Like uranium, plutonium can also be used to fuel nuclear power plants, as is done in a few countries. Currently, the U.S. does not use plutonium fuel in its power reactors.
What do we do with Plutonium-239 now?
… And much more convent than using a pig, unless you did not smoke cigars!