Kent Borg on Nostr: npub1aqc3u…ksngh "…natural materials such as wood and concrete." I get the wood ...

npub1aqc3uz9qe035vpngsqhpf7r5qel2dlmq86rzfq4j2qu662jq3uvq4ksngh (npub1aqc…sngh) "…natural materials such as wood and concrete."

I get the wood part, but concrete not so much. It might have existed way back when, in Roman seawalls (better than the stuff we make today), but I don't think concrete occurs in nature.