When your sim gains alchemy skill, the game will add debug spawners to your lot for alchemy materials . Apparently, it also does this on a houseboat. I had horrible lags when the game kept spawning collectibles on unaccesible tiles in mid air because of the size of the spawner. There's no way to get rid of them either, you delete them and they'll be spawned right back. I'm going to have to abandon my houseboat, and I really liked that houseboat
Also seasonal flower spawners seem to appear, but I only saw flowers growing in the sea after the alchemy debacle, so I'm pretty sure leveling alchemy just breaks the floodgates for your game to start adding spawners everywhere.
Beware if you want to have a bohemian houseboat witch :C
