Spider on DVDs

Staring at the book shelf full of DVDs (instead of books) for a moment, thinking of what to watch, I was wide awake. It was 12:45 in the afternoon, when all of the sudden, over the tops of the DVD cases crawls a medium-to-large black shadowy spider. It climbs face-down down the DVD case's spines and into the blackness of the shelf. It was so real that I gasped and asked my kids if they saw it or not. My youngest went and looked and said no, he could find no spider.