The ice structure pictured is 14cm long, it formed in a single night in this bird bath, and there is nothing above it that could have dripped to form a stalagmite. The triangular cross-section, and angle of lean also suggest that this did not form in the usual way for a stalagmite.

On the day before, the bowl was full of water and the temperature was a degree or two above freezing, overnight temperatures dropped to -2 C, skies were clear with no precipitation, the structure was fully formed the next morning.

I assume this is in fact an ice crystal, but how, and why, did it perform this gravity defying trick, and why don't we see such structures more often?