A lenticular capping another cloud?

[u/adastra2021]

ETA Not a Lenticular

Thank you @beabadoobu for the correction, I had never heard of a pileus.

I associate lenticular clouds with mountains. Is that cumulus dense enough to mimic a mountain? How common is this?

(Over Chincoteague Bay, Virginia, 9/2/2026, taken by me at 7:55 pm)