Center letter: u
Outer letter: a b e l m n
Answers (44):
  albumen
  album
  alum
  alumna
  alumnae
  annual
  annul
  bauble
  beau
  benumb
  blue
  bluebell
  bubba
  bubble
  bulb
  bull
  bumble
  bumblebee
  luau
  lube
  lull
  lulu
  lumen
  luna
  lune
  lunula
  lunulae
  manual
  maul
  menu
  mule
  mull
  mumble
  muumuu
  nebula
  nebulae
  nubble
  null
  numb
  ulna
  ulnae
  unable
  unban
  unman