tube body

Just saw these tubes and trails on my rock and sand. Then I saw this worm in the sand WHICH HAD SAND GRAINS GOING THROUGH ITS BODY. Do I need to be worried?

We were given a tank from a friend to take over for him when he moved out of country. Backstory to explain why we do not know much about where the rock originated or how old some of the fish are. ‍♀️ I’m hoping someone will know what this creature is in our tank!