These are an earlier form of the things -- glued rolls of scrap banana bark. (I've since figured out that the stems of banana leaves work just as well as manufactured frankenweenies.)
As the understructure of the "water" in my fiber sculptures, the frankenweenies add varying levels -- heights and depths -- to a piece. Using them I can make waves and ripples that look like they are moving.
Before I started using the frankenweenies, I had to lift up an already-glued-down surface "skin" piece of banana bark and stuff other odd bits of banana bark behind it to create raised or rippling effects. Many times I had to keep stuffing in more and more bits, lifting and then reattaching the skin pieces (and sometimes tearing them or wrinkling them badly) in the process.
Now I can lay down as many layers of the frankenweenies as I need to increase the variations of depth in a piece. I can then lay a skin piece over them, molding it to the underlying, rippling surface they make.
The glue I use makes the banana bark very strong and malleable so I can shove the layered frankenweenies and compress them down for different effects. They also work to add lift to craggy mountainsides and cliffs as well.