Remarkably adaptable, they are small in yeast cells grown on sugar, but grow large if the yeast is transferred to methanol.  
They often stand out in electron micrographs because of a crystalloid core made up of urate oxidase.  In germinating seeds, they are called glyoxysomes, since they convert fats to sugars as part of the glyoxylate cycle.  Remarkably adaptable, they are small in yeast cells grown on sugar, but grow large if the yeast is transferred to methanol.  For 10 points-name these organelles that break down many molecules by producing hydrogen peroxide.
They often stand out in electron micrographs because of a crystalloid core made up of urate oxidase.  
peroxisomes