HELP~ Sand Worms or Aliens are in my Tank!

Haha always good to know you dont have aliens in your basement, living room, etc....

 

also is the back of your tank clear or is it painted or have a back round on it, if its getting any sun through the window that will cause problems...

 

The tank is in front of a big window, the back is alge that has grown on the back, I have left it alone to keep it naturally blocking the sun, I need to add a back film sun blocker to the tank.

Who makes these backs to tanks?, I would like a blue one that looks like a picture of an ocean floor. Like a blue gradient, I dont want it too fake looking with coral and fish.