About: http://webisa.webdatacommons.org/296878449

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	My guess is what you got is a water stain where water gets under the sealer and darkens the color.
http://www.w3.org/ns/prov#wasQuotedFrom	howtocleanstuff.net