Cecedia, better known as galls, grow on plants infected with bacteria, parasites or insect eggs. Different species' galls are highly distinctive, often providing protection or nourishment for the creature growing within. Though frequently undesirable, they've also been useful to humans, over the years: ink is traditionally made using tannic acid from oak galls. The long-abandoned gall pictured above, photographed by nutmeg66 in Theddlethorpe St. Helen, England, shows the exit routes of whatever creatures it nurtured. Neuroterus numismalis galls on a leaf, shot by Mick E. Talbot of Lincoln, U.K. Galls take many odd shapes and sizes. This gall, spotted by Johann Dréo, hangs from the branch of an oak tree in Chamadelle, France. Silk Button Spangle Galls on English Oak, caused by the gall wasp Neuroterus numismalis. Uploaded to flickr with the understated title "Too many galls", anemoneprojectors's photo was featured here at BB early last year. "Here were so many galls on this tree that I actually felt sick," anemoneprojectors wrote. "But not too sick to take a photo!"