This is a slime mould (or myxomycete) which, despite the word mould, is not a fungus. It's in between the mobile, feeding stage and the final powdery, sporing stage. Might be Fuligo septica.
Must agree with Heino; this appears to be a Fuligo septica which will slowly darken in colour prior to sheading its dark spores when fully mature. Do hope you are able to observe it over the next few days and perhaps add some extra images.
This slime mould was recorded on 2 January 2022, (and only just uploaded to Nature Mapr when I got the App to work ) so I can't report on what happed after this observation.