Ok, here we go...
Found on saltwater beach. This thing seems to be sealed up quite well except for the dark "eye" in the middle on one side.
Don't know if it is from a dog collar or maybe a "tag" for a sea animal program if some sort. Seems to be well made and meant to be water proof.
Both sides are shown - I should have flipped the dime as well. I don't see how the thing is powered or how it would send information outside of its casing since there are no wires coming out. I guess that's why I thought it was a self-contained device.