About: http://webisa.webdatacommons.org/4006035

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	According to two reports in the original short story, their bodies consist of a form of matter that does not occur naturally on Earth; for this reason, they do not register on ordinary photographic film.
http://www.w3.org/ns/prov#wasQuotedFrom	wikipedia.org