This looks like a Peneroplis plantus foraminifera. It was found at Pago Beach on the island of Guam. Image is magnified 40 times under a ...

UPDATE: I am pretty sure my earlier identification is incorrect. I now think this might be an Elphidium aculeatum ( Polystomella aculeat...

This piece of Devonian Period limestone is from the Jeffersonville layer of Clark County, Indiana. It is unique in that it contains spines...