Im on a boat to visit you lawd. Itll take about 3 months tille we land.
Those are like the Blueberries of Mars. They are inclusions of whatever (lawdy;s, "The Hertfordshire puddingstone" is definitely a conglomerate of concretions of cryptocrystalline quartz like flint or jasper)
the ones found by our new member are also concretions in a matrix that were probably like >Itd take someone who is more familiar with the location to determine what they are(or else, take it to a Uni geology lab and have them do an x-ray diffraction analysis).As lawdy says, they are probably also flint jsper agate chalcedony , any kind of very dense quartz
Ive seen the Puddingstone gut and polished into table tops and it looks spectacular but they are a bit touchy an should not be used as weapons