Anyone have anything similar?

[kcb5150]

Got this in truly dreadful shape. Not hard to lap, slurry smells like wet plants. No layering in the sides but the colors shift subtly and there are intermittent fissures which haven't moved despite needing aggressive lapping. Was used with water but was stored who knows where with other oil stones of various types so there was minor cross contamination but it is accepting water without complaint. Bottom looks like it was cut with a geologist's hammer. Still need to tweak the lap and clean up vulnerable spots. I may seal it in some salt to try drawing out any other superficial oil. Strange, it reminds me of several things but nothing exactly.