An ice spike is a rare natural phenomenon and we were fortunate to wake up to see one on our bird bath the other day. Apparently they are known to occur more often on bird baths and drinking bowls put outside for pets rather than on larger bodies of water.
We had not seen anything like this before. It made the birdbath look more like a sundial. The spike measured just over six inches and remained intact all day, overnight, and only started melting the following day. It finally collapsed into what by then was a pool of water the following afternoon.