According to the name of the picture it's definitely a leather: "http://www.saltwaterheaven.com/photos/leatherbucket.jpg"
My guess is it's some sort of Sarcophyton sp., but that's just a guess as it's out of water and closed up b/c of handling. I have no idea how old that thing is either but man is it big!
A piece of rock fell in the middle of that leather and damaged it and then Ron cut it pieces and sold it all over the US, Alaska, and some countries in south America. I know that because I helped him cut it pieces. Now he has two babies of that one that almost half the size of mother. Check out his site for more pictures of that leather and others http://www.saltwaterheaven.com/
I too am a fan of softies. I am trying to get every type of leather I can find. Here is a pic of my toadstool (10" across when fully opened) and a couple of others.