Option 1: Starfish do have a skeleton called the endoskeleton. It is made up of calcium carbonate and is located internally.

Option 2: Sponges also have a structure called a skeleton, although it is not made of bone or hard material. They have a network of protein fibers called the spongin that provides support to their body.

Option 3: Jellyfish do not have a skeleton but they have a soft, gelatinous body with a central cavity called the bell. The bell is surrounded by tentacles that help them capture prey.

Option 4: Silverfish, also known as bristletails, do not have a skeleton at all. They have a soft and flexible body that allows them to move through narrow spaces.

The correct answer is option 4, as silverfish have no skeleton.