Cryoprecipitated is the cold-insoluble portion of plasma that precipitates when FFP has been thawed between 1-6C. It is extremely rich in fibrinogen and factor VIII. It also contains von Willebrand factor (vWF) and factor XIII.
"I made a mistake in an experiment, and instead of putting frozen plasma back in the freezer at the end of the day's experiment, I instead stuck it in the refrigerator. When I came in the next morning, there was all this junk in the bottom of the tube which I spun out, and I used the plasma for my experiment. My experiment didn't work because there was no Factor VIII in it. And I went back and fished the junk out of the trash and assayed the junk and got these outrageously high values for Factor VIII in the junk, and neither Charlie nor I believed it, and so it was one of those things. And sure enough, about a year later Judith Graham Pool discovered cryoprecipitate". 1
1. Reference: Resnik, Susan (1999). Blood Saga: Hemophilia, AIDS, and the Survival of a Community. Berkeley: University of California Press. pp. 40–41