Geb (gbb)
The first secure mention of Geb is in the 'Pyramid Texts' of Unis at the end of Dyn 5, where he is said to have 'created' the king (W 158), and the king's inheritance was from Geb and Atum (W 167) The king was Geb's 'seed' (W 208), the heir of his father Geb (W 211).
'Inheritance', 'heir', 'seed', in the context of the dead king, is the king identified with Osiris - Osiris Unis - Osiris was the son of Geb.
AFAIK, the only mention of Geb in a non royal context in the Old Kingdom, is from an inscription in the tomb of xnw dated to the reign of Djedkara the predecessor of Unis, or perhaps early Dyn 6: "an offering the king gives, and Geb....." (Htp di nswt Gb.....)
Apparently, Geb is shown in human form on a relief fragment from a Dyn 3 shrine of Netjerikhet at Iunu. A seated man / god wearing a long curved beard, has what may be the front part of a foot above his head - the upper part is broken off. In front of the seated man / god, is a text that reads: "I give life, stability, dominion, and joy for ever..."
The name of Geb was written with the 'goose' sign G38 (gb) + the 'leg' / 'foot' sign D58 (b).
All that indicates the seated figure is Geb, is a possible indication of the front part of the foot of the 'leg' sign D58. - seems a bit tenuous though - the figure could be Netjerikhet himself.
Eagerly waiting to hear from Hermione if the evidence for Shu is more explicit.
CT