mysterious growth

Would someone be able to help me identify this????? I saw this in my overflow today. What are these tube like things growing????

Alright so this tank has been running since July 4th, 2021. I don’t have sand in it because I am going to be moving this tank in the next 2 months and I figured I wouldn’t want to run it with sand to try and clean it all out just to put it all back in there(I know big mistake!!! Never starting a...