To understand what the barnacles growing on the Reunion flaperon can tell us about its history in the ocean, it’s important to have other pieces of flotsam to compare it with. Earlier, I posted a picture of a boat that had drifted across the north Pacific for about the same length of time as has elapsed since the disappearance of MH370. The density of sea life was far higher. But perhaps that’s due to the fact that it was immersed in relatively nutrient-rich waters. A more useful comparison might be to debris that has drifted in the Indian Ocean.
In May of 2013 a LeisureCat Sportsfisher motorboat capsized in a storm off the northwestern coast of Australia and drifted out to sea. (Many thanks to @Matty for bringing this up in the comments section.) Eight months later, it washed up on the shores of Mayotte Island, off the coast of Madagascar, as seen above. To put it in context, it started drifting 1700 nautical miles northeast of the current search area, and wound up 800 nautical miles northwest of Reunion.
One striking difference with the Reunion flaperon is the presence of an obvious waterline, above which no marine growth is present. You can see the barnacles and algae more clearly in the picture below:
I wish the pictures were higher resolution, but they seem to show goose barnacles that are at a similar density and size as those on the flaperon, and much smaller and less dense than those in the tsunami debris photo.
Here are a couple more photos of the same boat:
Note that the stickers and lettering have remained in place.