Fact 1: Adult sponges are sessile.

Fact 2: Sessile Attached permanently, immobile.

Given the two facts above, answer the question "What is immobile?" with the following options: 
- Fish
 - matter vibrating
 - Cats
 - Humans
 - an object
 - all matter
 - an organism's body
 - Adult sponges


 

        Adult sponges 