Implicit in all of this was a hell of a lot of robot activity, which was why Sean had taken the extraordinary step of traveling personally to Izzy to clean out Dinah’s supply of them before proceeding to his rendezvous with Ymir . The reactor had to be fed with ice. Because ice was a solid, it couldn’t flow through tubes. Robots had to mine ice from the shard and transfer it to a feed system: a set of augers that would move it into the reactor chamber to be melted and vaporized. A Siwi robot could move a lot of material in a hurry by embedding its "tail" in the ice and then using a whirring mill on its "head" to throw off a fountain of fine shavings that could be collected and carried off by Nats. The long intervals of time between burns could be used to store up a supply of shredded ice in hoppers that would feed the augers.