We collected an individual Polycera hummi, a subtropical nudibranch, in association with a green macroalga Ulva sp. from an intertidal oyster reef in Burtons Bay, Wachapreague, VA. The established range of P. hummi is based solely on a handful of records from Mississippi and Florida in the Gulf of Mexico and the Carolinas in the Atlantic Ocean. This finding marks the highest latitude that this species has been found, 350 km north of its previously established range from Mississippi to Beaufort, NC. We observed the individual actively navigate the Ulva thallus which had encrusting bryozoans (unidentified genus) and arborescent bryozoans (Bugula sp.)-likely prey species. We briefly summarize the current knowledge on this rarely encountered nudibranch, provide information on the collection site, including other sea slugs often encountered in this area, note its behavior and interactions with macroalgae and bryozoans, and suggest some fruitful avenues of future work on the evolutionary ecology of rare nudibranch species like P. hummi.