As I mentioned, my late husband was a Mason. I have moved several times and had to pack all our possessions, both when he was alive and after his death. I never found any skulls, bones, or other body parts anywhere--not stashed in closets, cabinets, chests, boxes, luggage, plastic bags, car trunks, ceiling spaces or other crawl spaces.
Some reasons for secrecy, even today: Some religious denominations do not want their members to be Masons, and will throw them out of membership in that particular church if they are. Also, the Masons do not want people claiming to be Masons just to take advantage of those who really are Masons. Over the years, I inadvertently learned several secrets, all of which are harmless. I respect their right to keep some things private, not because I am afraid any Mason will hurt me; I have been helped a number of times over the years by Masons.
I suggest that those who are curious attend those of their events which are open to the public. Talk to some Masons about their activities. Masons are very supportive of education and public schools. I have found Masons attending the same churches I have attended over the years. Masons belong to other organizations of which I am also a member. I always want to research what the always hazy "They" claim about people, organizations, institutions, art, books, to learn what is fact and what is not.
My husband received his MBA from USF. A few years later, someone began discussing Masons with a negative point of view; Roy indicated he was a Mason, and the information was incorrect. The other man, shocked, wondered why a Catholic was a Mason. (Catholics are allowed to join; the Catholic church does not encourage membership, along with certain other denominations.)Roy indicated he had never been Catholic in his life. The USF MBA was the "evidence." Roy reminded him anyone could attend USF.
This is a lengthy, but necessary, answer to some questions about a fine, but frequently misunderstood, organization. I am very proud and thankful to be a lifelong American citizen. This country began with some Masons as leaders--George Washington was one.