What might this be?

[Dustin Lane]

I bought some barn wood recently and when stacking it I noticed it had these little things on it. It looks like a cocoon from some insect but I don't really know much about them. Was hoping someone could help me out. None go very deep into the wood, pretty much just what you see. This wood came from a corn crib if that helps. Thanks!

[Chris Padilla]

Looks like they made holes in the wood...whatever it was! You might play around with Googling "wood insects" or "wood boring insects" or the something of that ilk.

[Steve Beadle]

Looks like a close-up of the surface of Mars to me.

[Chris Rosenberger]

Looks like termites to me.

[sean m. titmas]

Looks like a close-up of the surface of Mars to me.

just in case there are any living bugs in the wood you might want to sprinkle or spray some insecticide around the wood pile to prevent any contamination of your good clean wood.

[Mike Heidrick]

Some kind of wasp?

[Dustin Lane]

Here's what I've searched for and none of the images really match what I've got. Powder post beetles, round/flat headed borers, horntail wasps, and carpenter bees.
Could it be from the corn itself rotting/germinating?

[Jason Hallowell]

Chris R is right, subterranian termites. What you are seeing is reffered to as "tubes".

[Todd Burch]

+1 on termites.

Todd

[Dustin Lane]

It seems like a lot of entry and exit wounds to be termites. And the tubes don't extend at all like they do in other pictures I see of termite tubes. Here is another picture with my thumb for size reference. That is one that I pulled out of a hole.

[Steve Rozmiarek]

Those mud dabber wasps do something like that. Especially if the hole in the wood does not go very deep behind the tube, maybe they could be the culprit.