This watermelon (Citrillus lanatus) on my counter has been begging to be chopped open to celebrate summer's last hurrah as a fabulously drippy, sugary, watery dessert for the equinox dinner. Thanks, Plant Prop 1001, for giving us that opportunity. The seeds within this fruit are locked up beneath a thick rind, or exocarp, that will prevent the seeds from germinating unless the fruit decays or is split open. The open fruit allows for animals to eat the flesh with seeds, dispersing the seeds wherever they do their business, and exposing the seed to possibly the right conditions for germination.
An interesting note, according to Wikipedia, several watermelon seeds were found in King Tut's tomb. Perhaps they lay quiescent because they were housed in a dark, dry environment in the desert for hundreds of years. That's pretty cool.