Facebook stepped into Craigslist territory Monday with the launch of Facebook Marketplace, a formal section of the Facebook mobile app that is meant to replace buying and selling activities already occurring in Facebook Groups. But you know what people love to use the internet to buy and sell? Weird and illegal stuff, and sex! And quickly that's what happened, prompting quick apologies from the social media giant.

As Yahoo News reports, sexual services were some of the first things to go up on offer on the app, as if that were not inevitable. But people were also selling live animals, including at least one snake, and some baby hedgehogs.

Anyone remember Silk Road? For the limited number of users who were given the opportunity to use the Marketplace section of the app — it's scheduled for full rollout to users in the US, UK, Australia, and New Zealand in the coming days — they found illegal drugs for sale, guns, live dogs, and possibly an infant priced at $111, as the New York Times noted.

Facebook's director for product management Mary Ku issued an immediate apology Monday about the spate of illegal postings, saying, "We are working to fix the problem and will be closely monitoring our systems to ensure we are properly identifying and removing violations before giving more people access to Marketplace. We apologize for this issue.” Apparently, per the Times, "a technical issue had prevented Facebook’s reviewing system from identifying posts that violated its commerce policies and community standards."

From the looks of the last Facebook app update available to me today, that rollout still has not happened, so the fixes are still being ironed out. Marketplace will then be going live in the desktop version of Facebook at some point in the near future.

But given that Craigslist has two decades on Facebook now when it comes to community policing of illegal posts, it seems safe to say that problems will continue to arise.

And as the Times reported in July, Facebook and Instagram already had site-wide bans on gun sales instituted in January, which have been occurring frequently within Facebook Groups. SF-based web designer Mike Monteiro said he had been waging a campaign to flag gun-sale posts after the atrocity that occurred in Orlando in June, and he flagged about 500 of them in a month. According to Monteiro, Facebook only pulled down about two thirds of the gun postings, and only after repeated complaints.

Also, a ruse that seemed to handily get around Facebook's automatic systems that drug sellers might want to consider: gun sellers would put another object next to the gun, like a can of Hawaiian Punch, and claim that the Hawaiian Punch was the item for sale.

Related: Facebook And Instagram Now Ban Gun Sales Between Users