Fact 1: Adult sponges are sessile.

Fact 2: Sessile Attached permanently, immobile.

Given the two facts above, answer the question "Which is immobile?" with the following options: 
- adult starfish
 - all matter
 - adult goldfish
 - gastropod shells
 - tadpoles
 - adult sponges
 - an object
 - an organism's body


 

      adult sponges   