The answer is Glass!
Being neither a solid nor a liquid, but sharing the qualities of both, glass is its own state of matter.
When you hear the word "glass" you may think of window glass or a drinking glass. However, there are many other kinds of glass.
Glass is the term given to any amorphous (non-crystalline) solid that displays a glass transition near its melting point. This is connected to the glass transition temperature, which is the temperature where an amorphous solid becomes soft near its melting point or a liquid becomes brittle near its freezing point.
Most glass you come across is silicate glass, which consists mainly of silica or silicon dioxide, SiO2. This is the kind of glass you find in windows and drinking glasses. Glass is made by heating a mixture of dry materials to a viscous state, then cooling the ingredients fast enough to prevent a regular crystalline structure. As the glass cools, the atoms become locked in a disturbed state like a liquid before they can form into the perfect crystal arrangement of a solid.
Of interest, Walkie Talkie tower's glass panels reflect the sun leaving passers-by covering their eyes. The hotspot on Eastcheap is created by the glass windows recently installed on the south side of the 38-storey tower. Find out more here.