Because each staircase was constructed individually and entirely from wood, it is assumed that the staircase either broke apart and floated out of the stairwell during the sinking or disintegrated in the 73 years before the "Titanic" rediscovery. Another option is that whatever remained of the staircase was destroyed by the force of the bow hitting the sea floor and the huge hydraulic blast which resulted. Survivors described a large wave that swept the Boat Deck as the "Titanic" took her final plunge – this, or the wave produced by the collapse of the forward funnel, is often blamed for smashing through the dome and destroying the Grand Staircase. The surrounding foyers, with their oak pillars, plaster ceilings with oak beams, and chandelier ceiling fixtures all survive in recognizable condition.