I don’t want to nit-pick semantics but my brand of atheism didn’t find any meaning in the question you probably meant to ask and so I started fiddling with it to see if there is any way I might answer it with meaning.
If you define visitation loosely enough: photos, memories, dreams, and in caskets.
If you define sign loosely enough: old occasion cards, old notes, self written epitaphs.
If you define dead loosely enough then you might consider revival: clinical death, brain death, cryo. frozen bodies and heads.