What bird is a large mainly white seabird?

I found a bird egg in a marshland in the UK it is pure white and is 1 and a half inchs long and 1 inch wide can you please help me identify it? What is the adjective form of eagle? Who says these growing feathers plucked from Caesar's wings will make him fly an ordinary pitch? Is tweaty bird male or female? Is the hummingbird Thoth's sacred animal? How do geese know who flies in front? How fast is a white talied eagle? What does it mean when a duckling bobs its head? How can oil spills can effect seagulls? How high can egrets fly? How do you get feathers in birdland? What bird is called the bird of the sea? Who feeds the baby pigeons? Are owls noisy while flying? What did manny feel horrible about parrot in the oven? How many babies can Flamingos have at a time? Where do pygmy owls live? How do you catch a bush turkey? How does a kookaburra attract a mate? What ecosystem do kiwis live in?