Earth's extraordinary deep biosphere is our next great frontier

image via New Scientist

July 30, 2025, 6:00 PM

• •Karen G. Lloyd's book 'Intraterrestrials' explores the fascinating world of microbial life within Earth's crust, also known as the deep biosphere.
• •The book highlights the diversity and unique metabolic processes of these subterranean life forms, including extremophiles that thrive in environments without sunlight.
• •Lloyd's work emphasizes how studying the deep biosphere can reshape our understanding of life in general, revealing organisms with incredibly slow metabolisms.
• •Through engaging prose, the book provides a field guide to these hidden ecosystems, making complex biogeochemistry accessible and emphasizing their alien-like qualities.
• •The study of the deep biosphere is advanced by genetic sequencing and fieldwork, with researchers traveling to extreme locations to collect samples.

Karen G. Lloyd's book, 'Intraterrestrials,' offers a captivating exploration of the deep biosphere, the microbial life residing within Earth's crust. This hidden world, lacking sunlight, features a wide array of organisms with unique metabolic processes, challenging our perceptions of life. Through engaging descriptions and accessible explanations of complex chemistry, Lloyd reveals the alien-like existence of these subterranean life forms. The book underscores how understanding the deep biosphere can reshape our comprehension of life's boundaries, with extremophiles and aeonophiles showing us the possibilities of life.

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