Hello! I am not sure what that is. If I was wearing a latex / polythene glove I might give it a prod, to determine whether it seemed to be bone or plant matter or woody in consistency and how sharp. I'm glad that it has come up again, particularly if it is stiff (like a twig rather than like a piece of grass), because there is a concerning risk of stiffer objects lacerating the stomach wall etc. and causing peritonitis.
It would be helpful to know: 1) is there any more in there 2) could there be poison / drug / toxicity issues to deal with? For this reason, it's worth letting your vet triage the case. They might feel that they want to palpate your pets' stomach to see if there are any tender areas in case a radiograph is indicated.
Best of luck.
PS It is worth pointing out that most commonly, a dog vomits back something indigestible and just carried on with their life - however, as vets, it is our job to spot things that can go wrong before they go wrong, which is why a quick triage phone call is a good idea so that if your vet would like to carry out further checks, tor tell you some things to look out for, they can.