Marian Elizabeth (Glasheen) Havlik, known as "The Clam Lady," was born in Hiawatha, Kansas, on January 14, 1935, to George Elsworth and Elizabeth Rose (Kish) Glasheen. She earned a diploma in nursing from the St. Francis School of Nursing in La Crosse, Wisconsin, in 1955 and was practicing registered nurse in La Crosse until 1986, but was best known for her citizen scientist career as a malacologist.

Soon after earning her nursing degree, she married Joseph Anthony Havlik in 1956 with whom she had five children. Her interest in the field of malacology, the study of freshwater mollusks, began while helping her daughter with a science fair project in 1969. After that, mussel studies and fresh water environmental issues occupied most of her time.

Upon receiving a Bush Leadership Fellowship in 1976, Havlik went to the Ohio State University's Museum of Zoology in Columbus, Ohio, where she spent five weeks studying under the leading expert at the time, David H. Stansbery. Upon completion she began her independent study of naiad mollusks. Also in 1976, the Higgins' Eye Pearly Mussel was being considered for both federal and state endangered species lists.

Thus began her professional career as a consultant; she started her own business, Malacological Consultants, in March 1977, financed solely by her work as a registered nurse. Havlik began to work with the Upper Mississippi River Wildlife and Fish Refuge, the National Park Service, and state agencies in Wisconsin, Minnesota, Iowa, and Illinois. From 1987 on, Havlik spent all of her time conducting large research projects, the findings of which have resulted in many changes in state and federal government agencies to aid them with future projects and developments where there were known clam beds.

She testified for environmental organizations, concerned citizens, and government agencies. She lectured, published and presented papers, performed outreach, and taught at local schools and universities. From 1987 on, she spent all of her time conducting large research projects, the findings of which have resulted in many changes in state and federal management of freshwater resources, including river master plans, dredging practices and barge traffic patterns.

Her research interests were focused on the Upper Mississippi River System naiad mollusks, especially rare naiades; the preservation of ecosystems; and clean water and the monitoring of contaminants. She worked tirelessly advocating for the protection of the overlooked, yet vital species from developers, river transportation, and unmonitored commercial clamming that destroyed their habitats, thus earning her the title of “Clam Lady.”

In 2003 the Freshwater Mollusk Conservation Society presented Havlik with their prestigious William J. Clench Award "in grateful recognition of her longstanding commitment to the mussel fauna of the Upper Mississippi River system in the form of surveys, publications and unwavering advocacy for this important national resource."