Cell-counting factor that limits the maximum size of the multicellular structure during aggregation. Has a very low lysozyme activity. Hydrolysis of (1->4)-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in a peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrins. Monomer. Component of the counting factor (CF) complex, which includes cf60, cf50, cf45-1 and ctnA. In the absence of CF50, secreted countin is degraded suggesting that it may protect countin from degradation. Belongs to the glycosyl hydrolase 25 family. The gene for this protein is duplicated in strains AX3 and AX4. These strains contain a duplication of a segment of 750 kb of chromosome 2 compared to the corresponding sequence in strain AX2.