RK17 F0001 is a large concretion found during the archaeological excavation of the Rooswijk in 2017. The concretion is currently being excavated by conservators and archaelogists in the conservation facility.
In 2016 Dutch and British archaeologists undertook a survey on the site of the Dutch East Indiaman Rooswijk which showed it was at high risk. To address this a team has come together from Historic England and the Dutch Cultural Heritage Agency (RCE) to undertake an archaeological excavation in summer 2017. Follow this project on social media using #Rooswijk1740
You can read the press release about the project here: https://culturalheritageagency.nl/en/news/dutch-and-british-archaeologists-to-excavate-300-year-old-shipwreck-before-it-is-destroyed-by-t