A large cytoskeletal structure located at the posterior end of the perinuclear theca of a mammalian sperm head. The nucleus is tightly associated with the calyx, which contains calicin and basic cylicin proteins. [ http://www.ncbi.nlm.nih.gov/pubmed/9184090 http://www.ncbi.nlm.nih.gov/pubmed/12243744 ]
This is just here as a test because I lose it