Fact 1: Sponges are a source of food for many species of fish.

Fact 2: Like sponges, they are attached to the ocean floor.

Given the two facts above, answer the question "What organisms are a source of food for many species of fish?" with the following options: 
- remains of prehistoric life
 - whales
 - organic matter
 - sharks
 - gastropod shells
 - those on the ocean floor
 - Something made from fermented ricce
 - humans


 

      those on the ocean floor   