There is pink slime in my shower. What is it and is it harmful?

Say Goodbye to Pink Slime – Keep Your Surfaces Clean and Dry

To prevent the growth of the “pink film” in showers, toilet bowls, sink drains, tiles, and pet dishes it’s important to keep these surfaces clean and dry. The pink coloration is often caused by a bacteria named Serratia marcescens. This type of bacteria is naturally occurring and is found in dust and soil.  It travels through the air and thrives in moist environments. While it’s generally harmless, it can be unattractive. The best way to combat it is by ensuring proper ventilation and regularly cleaning surfaces alternating between chlorine-based products, like bleach, and nonchlorine-based products like Lysol.  Maintaining clean and dry areas discourages the growth of the pink film.