Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
5A) M31, a sample with no bioerosion; 5B) M35, a sample with a pattern of arrested bioerosion. In the latter image, etched mfds appear as dark irregular holes.
