313-million-year-old jawbone of an ass

Hammer time! But this is part of a crinoid or other echinoderm & the visible part is only about 1 mm long. Reddish-brown & with sediment welded to it--it sat out on the sea floor for quite some time. Tuscumbia Limestone, Mississippian, subsurface Walker Co., Alabama.

Crystals, small ones

Brick-shaped dolomite crystal encrusted by a fan of silica. Long dimension 0.1 mm (1/250th of an inch).

clams is teh awesome

Part of a clam, or a close relative, diagonally across the middle. The green is not Jello, but glauconite, a very pretty mineral that forms sometimes in seafloor sediments. From an ancient continental slope, now in western Alabama.

fossil coin

Not really. A discoid segment of a crinoid stem, one of a stack of calcium-carbonate "coins" made by an animal known as a sea lily. This is a small one, only about 1 mm across.