What do you use for a cave?

I am, at best, challenged when it comes to interior design, even with
aquariums. Lately, I've been culling out the plastics and replacing them
with naturals.

I'd like to also replace a Raphael Striped catfish that I lost a while ago,
and they like to hide during the day. I had a set of plastic rocks, (Still
do, actually, just not in the tank now) but what could I find that looks
more natural?

A