Seal is related to Skin. you are likely to find Bacteria in/at/on Skin. 
Irony is derived from Iron. Iron is a type of Device. Trap is a type of Device. Trap is related to Web. 
Seal <--RelatedTo--> Skin <--AtLocation-- Bacteria 
Irony --DerivedFrom--> Iron --IsA--> Device <--IsA-- Trap <--RelatedTo--> Web 