What Happened to Yosef Bones when the Took them out of Egypt ot actually when the Found them?
The Bavli, Sota 13, says (if I understand it correctly):
Come, see how beloved commands were to Moshe rabenu, for all the Jews were busy with spoils and he was busy with commands [specifically, filling the promise of taking Yosef's bones, see the beginning of B'shalach —msh210], as it says "a wisehearted person will take commands...".
And how did Moshe rabenu know where Yosef was buried? They said, Serach the daughter of Asher was left from that generation; Moshe went to her and said to her "do you know where Yosef's buried?". She told him, "the Egyptians made him a metal coffin and set it in the Nile River so its waters would increase".
Moshe went and stood on the Nile's bank and told him "Yosef, Yosef, the time that God has sworn 'I'm redeeming you' has come, and the oath you made the Jews swear has arrived. If you show yourself, good; otherwise, we're exempt from your oath". Immediately, Yosef's coffin floated....
Rabbi Nasan says, he was buried in a royal tomb. Moshe went and stood by the royal tomb and said "Yosef, the time that God has sworn 'I'm redeeming you' has come, and the oath you made the Jews swear has arrived. If you show yourself, good; otherwise, we're exempt from your oath". At that time, Yosef's coffin shook. Moshe took it and brought it with him....
The Tosfos Shantz (סוטה יג, א) says that they took the Bones of Yosef and placed it in the skin of a כבש (Goat I Think) the Animal then came alive with Yosef Bones in it and Thats why it says נוהג כצאן יוסף.