Invisible is a different concept from Apparent. Apparent is a synonym of Certain. Certain is related to Know. 
Needle is a type of Implement. Needle is related to Hay. Hay is related to Dried. 
Invisible <--DistinctFrom--> Apparent <--Synonym--> Certain <--RelatedTo--> Know 
Implement <--IsA-- Needle <--RelatedTo--> Hay <--RelatedTo--> Dried 