What is the plural of the French phrase 'un clou'?

des clous

The only Words ending with -ou when singular that are ending with -oux when plural: bijou, chou, pou, caillou, genou, joujou and hibou

e.g. un pou / des poux

Some Words are ending with -oux at both singular and plural, e.g.: courroux, saindoux