TPO-43 - Integrated Writing Task Agnostids were a group of marine animals that became extinct about 450 million years ago. Agnostid fossils can be found in rocks in many areas around the world. From the fossil remains, we know that agnostids were primitiv

There were three main assumptions that how agnostids may have been continuing living before they become extinct. All three reasons, however, were rejected by the professor because each of them had a serious problem.

As the passage suggests, acting as a predator might seem to be a good way for them to continue living because there were always different kind of marine preys for different agnostids to prey on. While it might seem possible, professor claims that it could not be possible as the agnostids did not have a good eyesight and sometimes they were completely blind. This is not possible to be a predator with poor eyes, specially when preys have powerful eyesight. There is also not enough evidence to prove that they had a special feature or ability to help them become predators.

Another assumption is that they have been dwelling on the seafloor. This claim is easily rejected by the professor. Agnostids were moving marine animals and they probably were fast. Seafloor dwellers are usually localized and move slowly and very often. It contradicts the agnostids charachteristics as they are fast and the chance of being localized in one place is very low.

The thirds and the last suggestion of the passage is that agnostids were parasites. They could live on others and feed off larger organisms. As the professor says, this is not possible. Population of hosts where large. There were a large population of agnostids that could not make living on low number of hosts.