The detailed sampling spots and sample characteristics are shown in Fig. 1a–b. Samples were observed under a transmission light microscope and exhibited typical morphological characteristics of filamentous fungi (Fig. 1c).Figure 1Specific locations of the sampling sites on the Nanhai No. 1 ship’s hull. (a) The platform of the shipwreck. T0101–T0602 are different excavation areas. We gratefully acknowledge Jian Sun from the National Center of Underwater Cultural Heritage for providing the image. (b) Images of six samples that were taken from the ship’s hull. Samples were taken by using sterile scalpels and placing them into 2 mL micro-centrifuge tube for subsequent microscopic observation, DNA extraction, and cultivation. (c) Transmission light microscope images showing fungal hyphae that had penetrated the wood structure. Red circles indicate fungal hyphae.