Memory Foam is a high density polyurethane foam sensitive to heat and pressure. An excellent material for memory foam mattress pillow top construction, it will return to its original shape with delayed resiliency. This characteristic allows a pillow top memory foam mattress to conform to the shape of your body, making an amazingly comfortable sleep surface. A pillow top mattress with memory foam contains an extra cushioning layer of foam. A pillow top memory foam mattress bed is the softest mattress available to the touch.