This is another gnome thread where lots of people have posted their gnome pictures over the years.
https://forums.thesims.com/en_US/discussion/678757/mysterious-mr-gnome#latest
It's in the store section.
There are several different magic gnomes that pop around the lot and do annoying things such as turn on the TV or stereo and links, that can't go into the fridge, appear all over the place too. They like to lie or stand in front of objects the sims need to use such as the shower or fridge, so if your sim can't have a shower, or something similar, it can be useful to go see if there is a gnome in the way.
Apart from the magic gnomes there are several different gnomes you can buy from the buy catalog, depending on what Expansions, Stuff Packs or Store content you have.
If you plant plasma fruit you'll get the vampire gnomes appearing and they do their thing which can make you either very rich or totally creeped out. They like to turn teddy bears into vampire gnomes. The way to get rich is to buy lots of teddy bears and place them anywhere on your lot. When the vampire gnome turns the toys to vampire gnomes, sell the extra vampire gnomes. You can make almost 1, 500 simoleans for each one. I think the cost of the teddy bear is about 40 simoleans and the gnome gets you a lot, I think it's 1,500.