Looks like one of the common caterpillars we call army worms. They do hide in the soil and are general feeders.

My first choice would be to tip the plant out of the pot and replant with fresh potting medium. Or, if the potting mix is a new batch, you may be able to simply sort through it carefully to find caterpillars and their pupae (brown, leathery oblong case).

hello ... thank you rhizo ... I did tip it out this was the only one in there, it was a small shallow pot ... the plants were re-potted into this mix about 3 weeks ago ...

I suspect that the caterpillar came from my neighbours yard because we have a large cement patio and yet the pot was almost next to the fence.

I will be much more careful from now on. :) thank you.