Barnacle Goose

A Barnacle Goose grows from shell-like pods attached to driftwood, ship hulls, and wave-washed trees. When mature it tears free as a black-and-white bird already capable of flight. A whole colony can strip a shoreline of food and cover a vessel's underside with weight. Sailors argue whether the creatures are birds, shellfish, or proof that the sea ignores mortal categories.

Sudden Flock: every creature within 10 ft makes a Quick save or takes 1d6 slashing damage from wings, beaks, and breaking shells.

Cut the Driftwood: destroying or separating the colony's host timber prevents Sudden Flock. Fresh water makes the attached pods close and become harmless for 1 hour.