That garlic...
the last few years I've been growing elephant garlic.
every year one or two bulbs haven't developed properly, and they've become just one giant bulb, like a clove, but in the shape of a bulb....
I always assumed it was poor growing, but plant them the followng year and they produce a normal bulb....
I suspect they grow naturally as a result of drought, some sort of deficiency or whatever and either the growers had a poor year and decided to market these bulbs in their own right, OR, more likely, they have found a way to artificially stress the plants to produce the mono-bulb....having realised that people love them.