Number of combinations created in this step: 13

451. Gas Mask = Activated Carbon + Rubber
452. Cows = Domestic Animals + Ruminants
453. Star = Helium + Hydrogen
454. Toy Ballon = Helium + Rubber
455. Ballon = Helium + Textile
456. Deers = Horn + Ruminants
457. Agricultural Land = Irrigation System + Humus
458. Wooden Bridge = Moat + Wooden Ladder
459. Wild Boars = Nonruminants + Nuts
460. Hippopotamus = Nonruminants + Water
461. Giraffes = Ruminants + Trees
462. Internal Combustion Engine = Steam Engine + Benzine
463. Organ = Musical Instruments + Tube + Tube