The Beecher bed is what paleontologists label a konservat-lagerstätte - a term from German meaning "conservation storage place." Lagerstätten are mother-lode fossil assemblages typically noted for exquisite soft-bodied preservation of organisms. This particular lagerstätte dates from the Late Ordovician Period (about 450 million years ago).
The Beecher bed is a 4-9 cm thick bed within the Frankfort Shale from a small quarry just outside of Rome in Oneinda County (43° 15.2' N, 75° 24.5' W). Here's a photo of the quarry from the Brigg's Lab website.
The amazing thing about the Beecher bed fossils are the fact that they're pyritized - replaced by the golden iron sulfide mineral pyrite (FeS2) - and often show soft-tissure preservation. Some 85% of the fossil specimens found are of one trilobite - Triarthus eatoni - although additional trilobites, graptolites, and a few other organisms are present as well.
Not only are the trilobites fossilized, but often antennae, appendages, gill structures, and even musculature is preserved in exceptional detail which is quite rare.
The neat images below are from Amherst College professor Whitey Hagadorn's research on Beecher bed trilobites. On left is a pyritized Triarthus eatoni trilobite. On right is an x-ray image of the same fossil showing antennae and appendages not visible on the surface of the specimen. Go to the website above to see the image rotate around for a 3-D view!