This is teredo wood. It started as ordinary driftwood, then shipworms moved in and burrowed their little tunnels through it. When the wood sank and got buried, those tunnels filled with mud and minerals… and the whole thing fossilized. Some teredo pieces end up full of agate. Some fill with mudstone and form perfect little agate rings. Every one of them is a time capsule of ocean life carving its way through wood and geology sealing it in. #OregonCoast #Beachcombing #Fossils #Rockhounding #geolo