Identification German WWI Artillery Shell casings brass and steel

Hello and thank for taking time to read this. I bought two shell casings at an online auction, one brass one steel, they seem to be from the same caliber, possibly 77mm? Any identification help would be much appreciated, thank you!

WW1/WW2 SHELL CASING: collection of 5 large WWI & WWII brass shell casing, including a US Navy 5 /54 caliber Mark 45 gun shell, good condition

Antique Shell Casing

world war one - What can I learn from these WW1 shell cases? - History Stack Exchange

WW1 Trench Art brass shell cases made into vases. Both made from German 77mm shell cases. Both marked Souvenir 1914/18. One marked Verdun - Rheims the other marked Arras - Yprern. 23cm

Identification German WWI Artillery Shell casings brass and steel - LATEST FINDS - U.S. Militaria Forum

Stewarts Military Antiques - - German WWII Brass Artillery Shell Casing, 1937 - $95.00

Could someone please help with an ID? - General Ammunition Discussion - International Ammunition Association Web Forum

Weapon - ARTILLERY SHELL & PROJECTILE, 1917

Original WWI U.S., British, and German Trench Art Brass Artillery Shel – International Military Antiques