hi! i took 2 hermit crab back to my tank last week..... 1 big like around 5-6cm and another about 3cm. the small doing find climbing around eating the algae but the big one can't climb and remain in the bottom. and I found out that it eats away my mushroom cause all of my mushroom dissapear day after day. Did i got the wrong hermit crab? if so how can I tell which one of those crab that can be use to clear up algea?