Fact 1: Adult sponges are sessile.

Fact 2: Sessile Attached permanently, immobile.

Given the two facts above, answer the question "what are immobile?" with the following options: 
- critical organs
 - all matter
 - land mammals
 - adult humans
 - gastropod shells
 - adult sponges
 - water molecules
 - an organism's body


 

      adult sponges   