A lot of scientific equipment is carefully designed to do exactly what is needed for the experiments in question. But sometimes regular objects work just as well, or even better. You’ll regularly find milk and nail polish in a cell biology lab, and fruit juice in a fly lab.
It seems oceanographers have embraced the rubber duckie as their tool of choice.
In 1992 a container ship traveling from China to Seattle lost a shipment of toys along the way. Among the toys were thousands of rubber duckies. The ducks, enjoying their newly found freedom, traveled along ocean currents. By 1995 they had reached the Bering Strait, and, trapped in the ice, it took them another 5 years to reach the Atlantic. In 2003, many of the ducks surfaced on beaches on the East coast of Canada and the Northern US. They were a bit faded, but still intact. Through the floating toys, researchers were able to learn a lot about ocean currents.
The lost shipment was an accident, but now NASA is purposely employing rubber ducks to track the flow of melted glacial ice. Initially, the team sent a probe with a sensor into the stream, but lost the signal. As a backup plan they sent 90 rubber ducks in the stream, in the hopes that people will find them and return them. The location of the found ducks will then show where the glacial water ended up.
Why do these ducks survive a trip through glacial ice? The manufacturer of the ducks that traveled the oceans between 1992 and 2003 says that the toys are made to withstand a two-year-old playing in the bath. I guess you can’t get a better quality test than eleven years on the ocean…