Why was the Ark and Table of Showbread covered with unclean skins before moving if all was Holy?!

The Talmud in Shabbat 28a concludes that the "Tachash" - a species with which we are not familiar, is in fact a kosher species. According to one opinion, the Tachash was a species created especially for the purpose of making coverings for the tabernacle, it had a multi-colored skin, and was quite beautiful.