Thank you to everybody who'd been posting their gnome pictures and commenting on this thread. I've been at work and now I'm about to go to work again so can't post pictures during the day. It's 5:25 now so will post a few here while I can.
Here's what I saw when my ghost gnome appeared. I think the snowmen were due to melt anyway.
https://s5.postimg.cc/uudf2nlqf/Gnomes_Screenshot-80_zps058fb618.jpg
As this particular game progressed, I noticed the ghost gnome seemed to become the gnome ring leader. There were lots of other gnomes in this game. I also noticed new ghosts appearing regularly. One of them was an elderly woman and since one of my Sims had accidentally cloned herself using the Science thing, there was a toddler. This elderly ghost would take much better care of the toddler than any of the young adult Sims in the household who all were much too interested in using all of the equipment placed around the lot.
I think I only got videos of her with the toddler though as I can't find any screen shots.
Actually this is another shot of the Vampire Gnome turning teddy bears. This is a great way to make extra simoleans you can buy the teddy bears for about 50 and sell the Vampire gnomes for about 1000. I haven't actually sold the vampire gnomes yet though as I like to keep them.
https://s5.postimg.cc/734e9optz/Gnomes_Screenshot-9_zps478f07fb.jpg
The pink rabbit is the ring in here - it isn't a teddy bear as it is a toy and she didn't turn it into a Vampire gnome - but she got the rest of them eventually. Only one has turned so far in this pic.
Here is the Winter gnome with a Vampire gnome flying behind him. He arrives when you have lots of igloos and snowmen on the lot.
This is where most of my gnomes come from. In this pic she's catching a deathfish. But in some games they seem to catch a gnome just about every time they go fishing in the wishing well. I just have to remember to check their inventory.
Mr Manchu from China dancing next to the wishing well. He came out of the wishing well along with the gnomes from all the WA locations even though none of the sims in the household has ever traveled to any of those places.
This gnome comes from the Spring Festival. This is the first of many of this gnome that the household brought home from the Spring Festivals. They seem to get them whenever they go hunting for Easter eggs.
This is a link to another movie of my vampire gnomes and the summer festival gnome. It is similar to the other movie, but it has more pictures of the gnomes in different poses.
http://www.thesims3.com/contentDetail.html?contentId=442437
It can be hard to open. I find if I right click the link and choose to open in a new tab, then wait a few seconds while it spins to load, then close the tab and choose open in a new tab again it seems to open straight away the second time.