I found this beautiful picture today when I was searching through symbiotic animal articles. It's a piece of a tree with tunnels carved out by Ambrosia Beetles. These beetles are symbiotic with Ambrosia Fungi which is only found in the xylem (defined by my MacBook as "the vascular tissue in plants that conducts water and dissolved nutrients upward from the root and also helps to form the woody element in the stem") tissue of dead or dying trees where Ambrosia Beetles have lived. The Beetles burrow into the wood of the tree to consume the fungi and lay their eggs (also interesting- these beetles are mostly asexual; they clone themselves) and in eating the fungi they store its spores in a part of their bodies called their mycangia and then travel to another tree to burrow again and transport the fungi and let it grow with other kinds of Ambrosia fungi. Through further reading I found that one researcher discovered that some Ambrosia Beetles have found a way to find already established tunnels with other fungi growing inside, eliminating the need for the beetle to carry the fungi to a new tree and create their 'fungus gardens'. These beetles have lost their mycangia through evolution.