Beta-glucuronidase involved in ulvan degradation (PubMed:31285597). Ulvan is the main polysaccharide component of the Ulvales (green seaweed) cell wall. It is composed of disaccharide building blocks comprising 3-sulfated rhamnose (Rha3S) linked to D-glucuronic acid (GlcA), L-iduronic acid (IduA), or D-xylose (Xyl) (Probable). Beta-glucuronidase removes GlcA side chains present on some O2 residues of Rha3S. Can remove the GlcA side chains from polymeric ulvan or from smaller oligomers (PubMed:31285597). a beta-D-glucuronoside + H2O = an alcohol + D-glucuronate By ulvan and rhamnose. Belongs to the glycosyl hydrolase 2 family.