Detect Flesh

For the duration, you know if there is any creature with flesh within 30 feet of you, as well as where the creature is located. Similarly, you know if a creature you detect is undead or not. Constructs, incorporeal undead, and creatures that lack flesh and bones are immune to this spell. The spell can penetrate most barriers, but it is blocked by 1 foot of stone, 1 inch of common metal, a thin sheet of lead, or 3 feet of wood or dirt.