Do you need a hermit crab sponge?

Land hermit crabs do not need a sponge in their tank. A sponge is high maintenance, it needs to be sterilized at least every 2 days due to they are known to harbor molds and bacteria. There are other methods one can use if they are attempting to boost the humidity within their tank.

That being said, if one is willing to do the high maintenance a sponge requires, it is a personal choice.