Wave buoy

When I returned to work, I fond this object placed more or less outside my office door! Initial feelings that it is an explosive mine from WW2 that was placed to lie in wait for me have been resolved by the knowledge that it belongs to the research lab through the wall next door. It is part of a Hebridean Marine Energy Futures initiative to measure the strength and frequency of waves off the west coast of the Hebrides. At least, that's what they're telling me!