Iron Golem doesn't appear as a huge hulking iron brute as in the villager golems but as a normal thaumaturgic golem. Please do not confuse these with the ones you make with 4 iron blocks and a pumpkin.
They move quite slowly and sink in water.
Thaumonomicon Entry Edit
"Iron golems are extremely tough and strong, able to carry huge loads. Their weight however causes them to move quite slowly and sink in water."
- Durability: High
- Strength: High
- Self-Repair: Very slow
- Carry Limit: 32
- Speed: Very slow
- Upgrades: 1
- Catalyst: 1 Iron Block
- Aspects: 4 Humanus, 4 Motus, 4 Spiritus