Hermit crab walking on mushrooms

[lostrider]

My new halloween hermit crab enjoys climbing the rocks in my aquarium (Fluval Evo 13.5 gallon) and has even walked along the silicone lining up to the top of the aquarium. Sometime his adventures have him walking on my Rhodactis mushrooms and they get upset when his claws step on them and when his shell slides along. It looks like they are spewing something from their mouths, but it eventually goes back in over time.

 

Should I consider replacing this crab with something smaller or perhaps looking at a snail instead? I like the crab but I don’t want it to trample future corals that I may buy. The rhodactis mushrooms don’t seem as big and happy as they were before. He has walked on them at least once a day since I brought him home. It isn’t that graceful and just trudges along with its shell when it wants to go somewhere. Or am I being too cautious? I have 4 snails as the other part of my CUC.

 

Thoughts?

 

The positives are he is a real character and he sifts my sand very well.