The Rhynie Chert (Figure 1) is a Lower Devonian (∼407 Ma) lagerstätte of early plants and their accompanying biota (Strullu-Derrien et al., 2014;Trewin & Fayers, 2015), preserved by early silicification from adjacent hot spring activity (Baron et al., 2004). The deposit constitutes the world's oldest preserved terrestrial ecosystem, including extensive evidence for the colonization of plants by mycorrhizal fungi (Harper et al., 2020;Krings et al., 2018;Strullu-Derrien et al., 2014;Taylor et al., 2004). Arbuscular mycorrhizal fungi evolved in symbiosis with early plants which were colonizing the Devonian land surface (Remy et al., 1994). The plants require trace elements, supplied by the fungi, while the fungi gain carbon from the photosynthesizing plant. Fungi similarly controlled nutrients that were required by animals in the Rhynie ecosystem (Strullu-Derrien et al., 2016). Fungi also contribute to plant resistance against contaminating trace elements (Colpaert et al., 2011;Hildebrandt et al., 2007;Neidhardt, 2020). It is important to note that much current work on the fungal response to metals relates to ectomycorrhizal or ericoid mycorrhizal fungi, which had not evolved at the time of Rhynie Chert deposition. This includes numerous studies on the fungus Aspergillus. However, there is also evidence that arbuscular mycorrhizae, which were present at Rhynie, influence the occurrence and speciation of numerous trace elements,