A Swellesley tipster set us into action earlier this week when we were asked about the following:

“On Wellesley’s Brook Path, about halfway from Wellesley Avenue to Brook Street, there’s a bridge over a swampy area. Just past the bridge, heading towards Brook Street, in the brook, is a two bladed propeller mounted on a large rock – and the blades of the propeller rise and fall, and splish/splash, as the water current goes by. Maybe it’s there for the fish, or maybe it’s there to make people walking by curious?”

My first thought was perhaps those innovative robotics students at Wellesley High had concocted something ingenious to help the fish. I hadn’t been by there or been aware of the device’s presence, but planned to swing by Tuesday morning to check in person.

In the meantime, another reader asked about the same thing, having noticed the fish making their way up the fish ladder in the brook: “I noticed this odd board that must be placed to help guide the fish? It’s sort of in the stretch behind Hunnewell school…,” wrote Steve Colbert, who shared the video below with his expert play-by-play.

From there it was on to Natural Resources Commission Director Brandon Schmitt, who delivered the definitive word on the situation: “In scientific terms, that is a stick… Interesting stick.”

Schmitt went on to say “I’m actually most impressed. We spent millions of dollars on the park to create ripples and rock vanes to make habitat and introduce turbulence and oxygen into the stream, and here is the perfect solution.”

Unfortunately for me, the show was over by the time I got there Tuesday morning, as the water was mostly still.

In the meantime, I did get an answer from Schmitt to another question that has puzzled many seeing the fish swimming up the brook: What kind of fish are they?

Those are are white suckers. “The state biologist who was looking at improving the fish passage confirmed that,” he said.

That’s what a kid had told us last year as well.

Enough of the serious stuff: Got amusing tips, photos, or ideas to share? Please send to [email protected]