Silver threads

I had these silvery trails all over carpets and chairs in my dining room once. My culprit was a huge slug and I think you will find that's what you have. I could never find it - so my solution was to wait until late evening when the rom has been in darkness for some time. When you go in and switch on the light he will probably be out and about and easy to relocate outside. Hope this works for you.

As Karen says you will have to wait until dark to find it. I had the same problem with a snail that had come in through an open window in our living room. Finally found it after weeks of yukky slime trails across the carpet.

It sounds like you have got a slug or snail, I kept seeing a trail on my carpet by the back door and couldn't find it till I looked on the wall behind the door and there it was a snail all closed up i removed it put it back outside, the following evening a snail was coming back into the house again going to the same wall, i think they like to eat wall paper because where it had been there is a small patch missing.
So now I'm on snail watch.

We had this too, the slug was living behind a bookcase and coming out at night to eat the cat biscuits and drink their water.

Many thanks for your helpful replies to the 'silver threads' on my carpet. I haven't seen them again - so hopefully it was a 'one-off' and it won't come back - if it does I'll know what to do!