A photo of this aquatic creature was shared on Facebook recently and generated an "OMG what is that" reaction.

The photos were shared on the You're Not Up North until you cross the Mackinac Bridge!!! Facebook page.

I'd never seen a fish like this, which was reported to have washed up along the shores of Lake Superior. Some guesses were that the creature is a mudpuppy, which is a salamander.

Other say the fish is likely a round goby, an invasive species in the Great Lakes. The fish is a native of Europe and found in the Black and Caspian Seas. The fish is considered a prohibited species in the state.

The University of Wisconsin took a look at what the round goby can do to the Great Lakes

To look at it, the round goby doesn't seem like much. A small fish the approximate size of an average pickle, it seems like the sort of creature that'd be the dominated in the aquatic universe, not the dominator.

But like an ecological David in reverse, the voracious goby has used strength of numbers to wreak serious damage on the gentle Goliath that is the Great Lakes food web. Sometimes found in groups of several hundred or more, round gobies have made short work of the key food sources that sustain the young of a lengthy list of Great Lakes sport fish: bass, walleye, and yellow perch. Round gobies also dine on sport fish eggs when the opportunity arises. These species are fighting back, feeding heavily on gobies, but goby populations are usually too large to be affected.