Indeed, even though the decorator crab species look like walking gardens, often what they attach are not algae but other animals: hydroids, sponges or bryozoans. These clever and gorgeous animals are very good at blending into their surroundings. As long as they stay in the general area of where they scavenged, the decorator crab can look near invisible. I was very lucky to find this decorator crab at a depth of about 20 meters , I took this photo with snoot to make it stand out from the cluttered background.