Who is Miss Peregrine, the Ymbrynes from Miss Peregrine's Home for Peculiar Children and what is their importance?

Miss Alma LeFay Peregrine is an Ymbryne, a sort of female "peculiar" with a wide range of abilities. Her "peculiars" include the power to transform into a bird, to move back and forth through time, and to construct and maintain the "loops" within which she and the peculiar children in her care can live in safety. She is described as ellderly, sharp tongued, loving and wise.