Jean, it could just about anything without a picture, past cultural enviroment and/or insects. Here is a website that was shared here on the board, thanks Tind, has photo's and a lot of info...
http://mrec.ifas.ufl.edu/lso/Manual/...-text-only.htm. I use a magnifying glass and flash light to see whats creeping around my chids. I am not very fond of anything that moves. Give the board a shout if you need help uploading...