Daf Yomi - Sukkah 50 - Was the Kiyor Covered?

Rabbi Dovid Meyers is the world's authority on the precise appearance of all the utensils that were used in the Mishkan. He told me that all the pictures of the kiyor have it with a cover, but he searched and could not locate a proof for this. Rav Getzel Fried cited a proof to him. The Gemora rules that if the water of the kiyor was revealed, it was left over night uncovered, the water cannot be used. The reason is because we are concerned that a snake drank from the water and left some of it's venom in there. Something that a Yisroel cannot dring is unfit to be used on the mizbeach. It is evident from this Gemora that the kiyor normally had a cover. It is still not known what it's dimensions were, but it certainly was covered.