I'm not sure how to massage the game into this state, but save attached.
I have a conveyor that I put ice on to add it to a large pool at the bottom of the base. The conveyor loops through 50+c fluid, and normally the ice quickly melts off and disappears from the conveyor at the bridge. However, I have several pieces of microgram sized ice on the conveyor that have been on the conveyor for 100+ cycles. They maintain their original temperature and will not heat/melt.
My guess would be that somehow barely over 20kg ended up in the source, so one of the conveyor tiles outputted was very small--or that the rest of the ice melted off but a small amount was left.
Unsure how to get it in this state, but have microgram (possibly milligram) sized bits of ice on a conveyor through a >0c environment.