Giant Red Hermit Crab

Giant hermits outgrow their shells fast enough that keeping a stockpile of larger empty ones on hand isn't optional — skip it and a crab this size will either squeeze into something too small or, worse, evict a snail that's still using its shell. The tradeoff for the extra real estate it needs is an algae-grazing appetite to match its size, making short work of turf algae a smaller hermit would barely dent.

Care level: Easy · Temperament: Peaceful · Max size: ~4" · Min tank: 30 gal · Reef safe: Yes · Diet: Omnivore, algae + scavenger