How to work with a list of base class, if a variable is only found in some subclasses?

Hi! I'm new and I'm working on a small strategy game where I'm making different units. All my units derive from the Troop Class. The specific units can be three types that are subclasses of Troop: Living, Demon and Undead. These have further Subclasses, which are the specific kinds of units, such as Goblin : Living.

My problem is, that some subclasses have their own variables, such as Living has foodUse, that the others don't have. When I try to loop through a List(Troop) looking for the amount of foodUse in each instance, it will give an error, that Troop doesn't have a variable for foodUse. This is understandable, as the variable only exists in the Living subclass. Is there a way for such a loop to only look at instances of Troop that happen to have foodUse, and disregard instances that don't? (While still using List(Troop) instead of List(Living) ?) Or maybe there's just a better way of doing this than the subclassing I'm doing? Thanks!

 public abstract class Troop : UnitBase
 {
     string[] _name;
     string[] _tags;
     int _type;
     int _hp;
     public DamageType damageType;
     public enum DamageType
     {
         Slashing,
         Piercing,
         Blunt,
         Magical,
     }
     
     public string[] name { get => _name; set => _name = value; }
     public string[] tags { get => _tags; set => _tags = value; }
     public int type { get => _type; set => _type = value; }
     public int hp { get => _hp; set => _hp = value; }
 }



   public abstract class Living : Troop
     {
         float healMultiplier = 1f;
         public int foodUse;
     }
     
     public abstract class Demon : Troop
     {
         float healMultiplier = -1f;
         public int apetite;
     }
     
     public abstract class Undead : Troop
     {
         float healMultiplier = -0.5f;
     }

The specific unit types then inherit from these:

 public class Goblin : Living
 {      
     public Goblin(Alligeance thisalligeance)
     {
         alligeance = thisalligeance;
         name = new string[2] { "Goblin", "Goblins" };
         hp = 8;
         damageType =  DamageType.Blunt;
 foodUse = 1;
     }
 }

In other class:

    foreach (Troop unit in troops) { food -= unit.foodUse; } //Throws error, not all units have foodUse.