The Happy Scientist, Robert Krampf, has a lot of neat and useful stuff on his site, but one of my favorites is his science photo of the day. Here's an example--
[Robert's wife] Nancy found this marvelous object on the beach. What is it?
This is the lower jaws of a Black Drum fish (Pogonias cromis). These incredible fish have powerful jaws with lots of tough, rounded teeth. This lets them eat oysters, mussels, and other shellfish, crushing the shells in their mouth. The teeth and jaws are commonly found as fossils, but their strange shape makes it hard to identify them unless you are familiar with this fish.