A microbial mat is a multilayered, thin sheet composed of aquatic microorganisms—most predominantly bacteria and archaea. Although nearly microscopic to the naked human eye, this small coating of microbes can proliferate within a conglomeration of chemical environments, independent of temperature and predators. When you are a child rinsing your hair with the clear saltwater of the summer’s ocean, and a sliver of it becomes coated in a green, mildew consistency, that’s our fellow microbial mats, coating your hair follicles in archaic bacteria. 

At just shy of twenty-three, my sister, Madelina Marquez, began her PhD in ecology at the University of North Carolina, Chapel Hill. When she graduates, she will be the first of our entire family genealogy to finish with a PhD. If—Madelina would clarify—if I graduate. This is a disagreement we often have. I find it ironic, frankly, that Madelina—headstrong Madelina, unrelenting Madelina, the Madelina that would rule our playtime operations with an iron fist—has any doubts regarding her intellectual capability. 

Madelina chose microbial mats for her research topic. Because, of course, Madelina would choose the most overlooked, environmentally-neglected area of study offered at her university. A forgotten species festering in a forgotten environment. When was the last time you thought, meaningfully, about the importance of cyanobacteria and nutrient cycling?

 

“But they’re so important, Isa. They’re responsible for nearly every aquatic organism’s survivability,” Madelina reasons as we drive along I-95, her seat pushed almost comically forward, small hands gripping the fluffy steering wheel cover.

I’m reminded of Madelina at thirteen, pushing away Dad’s can of ravioli with the assertion that she was “vegetarian now” and didn’t want to condone the suffering of any animals. The cheap tomato sauce and meat paste sat tasteless on my tongue as I recalled our earlier visit to the dairy farm. I had been afraid to pet the cattle initially, gripping onto Madelina’s coat as she fed them dried corn from her cupped hand. When the calf’s tongue met her open palm, she held steady against it, unafraid.  

“Look at their eyes, Isa. It’s so, so sad how people treat them,” Madelina confided in the space between us and the calf’s cage.

“It is a cow,” I answer, as if that justifies the act of imprisoning a living being inside a 3 by 2 feet pen. I am surprised by the expression of disappointment on her face.

“It’s a person, Isa. It has thoughts and feelings and a family. It should be out there—in nature. Not stuck here, behind metal bars.” As if to emphasize her point, Madelina lifts the calf’s chin, and it follows without restraint. 

I had not considered a cow to be anything beyond an animal with four feet, a long pink tongue, and low-hanging udders for milk. I had not considered the fact that I could and should care for something that isn’t decidedly human. But Madelina already had, at the tender age of thirteen. 

At her encouragement, I lightly scratch a patch of dark fur behind the calf’s ear. I feel warm and raw when it pushes its head into my outstretched palm. Maddy tells me I still have a lot to learn. I don’t disagree. 

During the fall of Madelina’s sophomore year of college, she brings home a kitten—barely two weeks old. It’s still blind and practically immobile. I love her. My mom rolls her eyes at the kitten before taking it into her hands anyway. “Not another one of your strays, Maddy,” she scolds. 

This had become a habit of hers. At 15, Madelina brought home an old, forgotten rat named Waffle. He was impressively ugly and his long tail reminded me of cheap rubber. Yet, five weeks after his arrival, he slept in bed alongside me. I follow in Madelina’s shadow and find myself falling in love with animals I never thought I could. She constantly guides me forward with patient hands. 

At 20 years old, Madelina does the last thing I ever expected her to do.

She breaks up with her long-term boyfriend, Brandon. She tells me this casually while driving to Santander Bank. 

“Why?” I ask. Madelina’s eyes remain steady on the road, fingers tapping along to Rainbow Kitten Surprise’s tenor singer. 

“He loved me. I liked him,” she answers, voice unenthused. It feels like my world has gone slightly off-kilter. Madelina, my Madelina. The same Madelina that chose the ugliest betta fish at Petsmart because “no one else would” and housed two friends within her 200 square-foot dorm when they were homeless—that Madelina found something she could not love.

Two days after that conversation, she leaves for a summer-long internship on a secluded island off the coast of Lake Michigan. Beaver Island—with a population of 551. Madelina spends her days collecting water samples and investigating human and gull fecal matter within the island’s water supply. The work is grueling, the pay unimpressive, and Madelina spends her mornings in a green wetsuit wading through the murky algae. 

The nights, however, are when she has the most fun. During her first few days, interactions are stilted amongst the other student interns, conversations reduced to polite small talk and quiet meal times. By the third day on the island, though, a brave intern suggests a game of Uno, which Madelina and her closest confidant, Isabelle, join. By the fourth night, the students build a campfire along the shore, with a bottle of communal wine passed around like gossip. Under the clear night, Madelina traces the stars in the sky with her pointer finger, shoulders swaying to the beat of the Bluetooth speaker buried in the sand. After, Madelina swears she can feel the breath of the island, taste the salt of the ocean waves, and smell the sap of the nearby maple trees. 

It’s almost religious, she writes in her journal during her second week. The trees and the water and the people. You can’t run away from yourself on the island. You’re stuck with you, whether you like it or not. 

 

The same routine continues for the entirety of her summer: sleep, eat, work, hike, repeat. Time moves slowly on the island, hours dripping like syrup from a glass bottle. She loves it. 

When she eventually returns home, nearly 60 days later, I waste no time rushing to greet her at the airport. Madelina is all tan skin and bright eyes and she smells vaguely of the Virginia beach we used to vacation to. Later, in the quiet of her bedroom, she relays to me the secrets of her trip. I listen, fascinated. I’m half tempted to pull out my journal and take notes. 

“It was, like, life-changing, Isa. Seriously, I didn’t want to leave it,” Madelina explains. I nod but am unable to empathize. I cannot imagine wanting to live in any place other than home—with Nigel one floor below me and Mom and Dad down the hall. 

“We missed you a lot. It was really boring here,” I confess, because it’s true. Never in my fifteen years of life had I ever experienced a summer without Madelina. The season felt unnatural. 

Madelina softens at this. “I missed you guys a lot too. I wrote about you in my journal, like, every day.” I perk up at this. I hadn’t anticipated that Madelina thought about me as often as I had her—I assumed she was too busy finding the cure to cancer or solving mortality. 

“Really?” I ask, voice hopeful. Madelina scoffs. 

“Uh, yeah. Trust me, Isa, no one on that island is better than you.”