What is it about?
This study reports the discovery of Lophiostroma leizunia, the oldest known stromatoporoid sponge (extinct marine organisms with densely layered skeletons) that lived approximately 480 million years ago in what is now South China. These ancient sponges built complex reef structures and uniquely constructed their skeletons using fluorapatite, a phosphate mineral previously unknown in sponge biomineralization.
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Why is it important?
This discovery pushes back the fossil record of reef-building stromatoporoids by about 20 million years and establishes sponges as the first animal phylum known to have utilized all three principal biominerals: silica, calcium carbonate, and calcium phosphate. This demonstrates remarkable evolutionary versatility when most animal groups specialized in just one material. The finding also reveals that the transition from microbial-dominated to skeletal-dominated reef ecosystems began earlier than previously recognized, suggesting South China may have been a biodiversity hotspot for reef-building organisms during the Great Ordovician Biodiversification Event.
Perspectives
The finding of phosphatic skeletons in these early stromatoporoids opens new questions about biomineralization pathways in early animals. It suggests that genes enabling both calcium carbonate and phosphatic biomineralization may have been present in many early animal phyla, as sponges are considered to be one of the most ancestrial animals. Future research might explore why phosphatic skeletons became less common over time, potentially due to changing ocean chemistry favoring carbonate-based structures. This discovery may lead to reevaluation of other early reef environments and biomineralization strategies.
Jeong-Hyun Lee
Chungnam National University
Read the Original
This page is a summary of: Phosphatic stromatoporoid sponges formed reefs ~480 Mya, Proceedings of the National Academy of Sciences, March 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2426105122.
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