I learned this the other day and to me, this is nothing less than mind blowing. You know loofahs, the things you scrub with in the shower? You might have thought they were a sea sponge, or something similar, right? Oh no, my friend. A luffah is a tropical vine that bears a fruit that can be eaten, or dried and turned into a shower sponge.
I know, I know, how bizarre is that?
If you don't believe me, here is a picture of the fruit, lifted from wikipedia...
Apparently, you can get the seeds, plant them, and it grows as a vine. After they mature, you can harvest them, remove the fleshy part of the fruit, and dry the rest. I found step by step instructions here at Groovy Green (which also has some interesting instructions on things like making a compost heated shower- an idea I was slightly less enthusiastic about).
I guess you learn something new every day!