This is an interesting one comprised of a variety of materials. This is either an early soft body design for the POTF2 Jabba, or part of the design process for the EP1 Jabba Glob figure. This is all soft body except for the arms which I believe are hard copies.
The POTF2 Jabba was made of hard plastic, with a segmented tail. This piece is soft body, with a tail that is one piece like the EP1 Jabba Glob figure. However, the head and arms of this piece are the POTF2 sculpts.
It's painted with a green substance which appears to have been applied thicker and shaped on the bottom of the figure. Inside the body there is a hard plastic section of a pipe which holds the shape of the body. There is also an unknown substance where the head connects to the body which looks to have been used to get the sizing right.