Did you know?
The altar cover is always white and is, traditionally, made from linen. The reason why linen is used? Because the body of Jesus was wrapped in linen when his body was taken down from the cross.
Also, in France a tradition was established of holding the Eucharist in such high esteem that people would not receive the Eucharist when attending Mass, at all. Instead, they would kiss the altar linen at the end of the Mass.
Further reading….
http://www.newliturgicalmovement.org/2017/10/the-art-of-making-altar-linens-as.html