A fuzzy, white blanket

There is nothing that compares to a bite of fresh, vibrant fruit on a gentle spring day. Yet even during the chilly months, my sweet tooth never stops. So you could imagine my excitement when my roommate gifted me with an armful of blueberries, raspberries, blackberries, and strawberries. 

I stashed them in my fridge only to discover a couple of days later that there is a reason why fresh fruits are always the best fruits. To my dismay, I opened a pack only to find them covered in a fluffy, white blanket. Of mold. It was not the most appealing sight, and combined with the heavy smell of overripe strawberries, my stomach turned just a bit. 

Mold is a common nemesis to any fruit-lover (or vegetable-lover), and buying and consuming fruit is always a race to stay one step ahead of the mold that somehow lurks in every corner of the house. This observation led to a question I had never asked before: what is mold anyways? And how can it just appear like a phantom ghost devouring the best that the earth has to offer?

There are thousands of kinds of mold, some harmful (black mold), some delicious (blue cheese), and some medicinal (penicillin). For the most part, however, they are heavily avoided.  This is because mold can cause serious illness in humans, and since everything is susceptible to its stealthy invasion, much care must be taken to prevent it from growing.  

Mold is a kind of fungi and participates in the degradation of anything organic. As such, mold only needs moisture and an organic substance to thrive. Mold is made up of branched, tubular hyphae. Combined together, they are called mycelium, and there are two types: vegetative mycelium and aerial mycelium. The first roots the mold to the substance it feeds off of and absorbs the necessary nutrients for it to grow, while the latter is charged with reproductive tasks, such as producing spores. Both of these parts of mold work together to create the fuzzy fungi that can grow anywhere from damp walls to rotting fruit to even human feet.

This is the structure of one of the common molds found on foods. Provided by https://etc.usf.edu/clipart/

Invisible mold spores are everywhere in the air, giving them opportunity to invade anything. And food products, especially ones as delicious as my ripe, red strawberries, provide the perfect moist and nutrient-dense environment for spores to thrive. The spores simply have to land on the food and start growing. The fuzzy white or gray part that we see is the mycelium extending to release more spores into the air. 

The Foldscope gave me a front-row seat to this strange organism. As can be seen from the images, the hyphae of the mold resemble a woven lattice of tendrils, some which twist into a rope-like structure. 

Fungi are responsible for cycling nutrients through decomposition, which makes important nutrients, such as nitrogen and phosphorous, available for other organisms to use. They are an essential part to ecosystem survival. These mysterious dwellers are found in dark and damp places, and their close relationship with dying things give them an eerie quality. And yet, they remind me of the beauty of the harmony found in the world around us in an ever-circling pattern of life and death. And all this from a sweet strawberry hiding under its fuzzy, white blanket of mold. 

I conducted this project as part of Professor Pringle’s EEB 321 class at Princeton University.


Ecology of Fungi, Lumencandela.


Molds, Libretexts.


Are molds on foods dangerous? University of Minnestoa Extension


Learn About Mold: The Mold Life Cycle, Stern Mold, The Mold Information Resource


What is mold? Belfor Property Restoration


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