rockhead

The surface of the bedrock beneath soil cover.

This type of area, with reasonably well-defined rockheads under glacial and lacustrine deposits, probably represents optimum conditions for the adoption of seismic exploration techniques.

The fish Bothragonus swanii, a variety of poacher.

A stupid person.

Men seemed just as superfluous as women, a bunch of rockheads running around punching each other and getting hot and sweaty about guns.

A fan of rock music.

[…] an apparent betrayal of electronica's more oblique, less suburban ethos in favor of a record the rockheads like.

The rarest species was a Protestant although I'd bet that the majority of Ivy League rockheads in the 1950s were Prots.