One of the most damaging events to every strike mormonism was the discovery of the Rosetta Stone, which allowed scholars to translate ancient Egyptian and the resurfacing of the papryus that Joseph Smith claimed to translate in what is now know as the Book of Abraham and is given status as holy Scripture on par with (or even above) the Bible. The facsimiles that Smith used are reproduced in their Scriptures, complete with explanations given by Smith. A picture of one of the papryi appears at the right, you can look at the "translations" and the other facsimiles on the mormon webpage here.
The problem of course is that when any Egyptologist examines these documents, he or she will tell a much different story than Smith. Check out the video below from the Mormonism Research Ministry regarding the "Book of Abraham" It is impossible to explain away for mormon apologists, but they have to desperately defend it to prevent Smith from being shown to be the complete shyster he is.
