Samples

Thanks to all who looked and pondered - and in advance to RP1's brother who asked for more information.
I weighed the one on the bottom row, centre.
It is 200gms.
I placed it into 300mls of water and it displaced 185 mls...
You'll notice that they have a kind of circular shape and often some kind of depression near the centre... some of them spookily look like eyes.
Looking forward to hearing from him soon