Oviposition eggs can be made of silicone or glycerine or a dissolvable substance. For plays where you use multiple eggs, dissolvable ones are advised since silicone ones can get stuck if they go too far up the colon. The human body naturally tightens up to prevent intruders from exiting so they can destroy it so it might just squeeze down and keep it in if it’s silicone. Think of how popping boba is liquid in a jelly like substance. The eggs are made differently but are usually the jelly like substance filled with lube. (As far as I know since I haven’t ever used them but I am interested in them)
To anyone interested, see more information and pictures at the link below:
https://www.reddit.com/r/todayilearned/comments/8y6rzv/til_that_there_is_an_emerging_fetish_called/
ooh… ohhhh, so they are real eggs? hard boiled ones? and the eggs can dissolve!