In Attack on Titan, why does Eren's founding titan form look like that

Eren Yeager's Founding Titan Form & Powers eren founding titan TITAN WITHIN HER HER HARDENED STATE WAS UNDONE BY THE POWER OF THE FOUNDING TITAN , WAKING HER FROM HER FOUR YEARS OF SLEEP HOLDS THE CART TITAN WITHIN attack on titan 2 Eren Yeager Rumbling Founding Titan Wood Carving Included is a base made especially for the Art Piece, and a base stand I will include instructions on how

difference between With the power of the Founding Titan, Eren became virtually unbeatable, commanding legions of titans and possessing the ability to summon dead shifters from the