Salaah On A Memory Foam Musallah

If the memory foam Musallah is such that when making Sajdah, a person feels the firmness of the ground; i.e. his forehead does not keep sinking into the softness of the mat; but rather it reaches a point where his forehead is firmly placed onto the hardness of the ground and it cannot depress any further; then it would be permissible to perform Salaah on it.

However, if it does not have these qualities, then it would not be permissible to pray Salaahon it.