The temperature influence on the acoustically amplitude dependent sound speed of a marble rod was investigated. The sound speed was monitored through the resonance frequency by a series of ultrasonic frequency sweeps with successively increasing amplitudes. For the temperatures from 15 C to 60 C, the resonance frequency was measured in 5-degree increments as a function of the resonant acoustic amplitude inside the marble rod. In most of the curves the marble exhibits a softening (i.e. the sound speed decreases) with higher amplitude, but for each test run there exist one notable exception - for one temperature - where the marble gets stiffer (i.e the sound speed increases). The test also shows that the average sound velocity level first, as expected, decreases with temperature, but for the higher temperatures it increases - to well past the starting value.