Green when young, and about the size of an adult human's hand when full-grown, Dryococelus australis is more commonly known as the Lord Howe Island stick insect, or the tree lobster. Courtesy of Rohan Cleave/Melbourne Zoo hide caption

toggle caption Courtesy of Rohan Cleave/Melbourne Zoo

Victoria, a 2-year-old rat, sniffs for TNT, sticking her nose high in the air to indicate she's found some. She works her way down a 10-meter line with a handler on either end, and is able to detect the presence of TNT at a distance of approximately half a yard. Michael Sullivan for NPR hide caption

toggle caption Michael Sullivan for NPR

In the study, muscle cells were injected into the cell-free "scaffolding" of a rat limb, which provided shape and structure onto which regenerated tissue could grow. Bernhard Jank, MD/Ott Laboratory, Massachusetts General Hospital Center for Regenerative Medicine hide caption

toggle caption Bernhard Jank, MD/Ott Laboratory, Massachusetts General Hospital Center for Regenerative Medicine

Gerbils are harmless... Right? Peter Knight/Flickr hide caption

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Who, me? The Asian relative of this domestic gerbil is a well-known host to the bacteria that cause plague. Valentina Storti/Flickr hide caption

toggle caption Valentina Storti/Flickr

New Yorkers can take city-run classes to learn how to make their homes and businesses less attractive to these guys. Ludovic Bertron/Flickr hide caption

toggle caption Ludovic Bertron/Flickr