A conversation he had with Conoy and Spire at the Southern Observatory reveals that counter-clockwise tornadoes sink objects below the current on Giant's Deep. He posits that the Eye of the Universe does not want to be found. Cassava suggest building the Orbital Probe Cannon on Giant's Deep as it is the furthest planet and has no moons, aside from the occasional Quantum Moon.
During the end of construction of the cannon Cassava revealed they had given up hope it could be done and congratulates the crew and Daz attempts to cheer him up. Cassava finds Avens and Mallow's relationship too "gooey".
He decided to stay on the Construction Yard after the postponing of the Ash Twin Project, Daz came to join him and that is presumably where both of their remains are.