Animals of this and similar species of Antarctic sponges grow extremely slowly in the low temperatures. Estimates based on growth rates suggest a very long lifespan in this and similar animals. One two meter high specimen in the Ross Sea was estimated to be 23,000 years old, though because of sea level fluctuations in the Ross Sea it is unlikely that such an animal could have lived for more than 15,000 years [0688]. Even if 15,000 years is an overestimate, which may well be the case, this specimen appears to be the longest-lived animal on earth.