A pineapple-sized fungus has quietly grown undetected in the forests of southwestern China – until now. The massive mushroom may set a size record for a major branch of the fungal family tree.

The fungus — named Dianjunus rex — may also represent a previously unknown family, researchers report September 28 in Frontiers in Fungal Biology . Fittingly, D. rex is part of a lineage that split off from other fungi right after the dinosaurs — like T. rex — went extinct.

In 2024, researchers in China were conducting a survey of fungal diversity in a tropical rainforest in Yunnan Province when local farmers tipped them off to an unusual fungus in the area. The farmers included photos, says Indunil Chinthani Senanayake, a mycologist at the Kunming Institute of Botany in China.…