Tim, it’s supposedly meant to be rocks. My one went in the bin when I built the original Zvezda kit, which is kitted as the Z17, so not relevant to the actual ship.
Looking at this I may have to build this kit again as there was no dedicated pe available when I did mine, I just used bits and bobs from general sets.
It isn't that bad a kit Luciano, and I recon with the WEM etch, and a few bits and pieces from the spares box, It will come out ok.
Thanks for looking in Mate.