Where did you find this?

City, state, country

If it were near me, I would call it a "mud dauber" nest - mud daubers are various species of wasp that build small nests of mud for a single egg, fill it with insects and seal it up.

Thanks I'm in SW Turkey similar location to say Northern California. these fell out of some towels have been stored in our bathroom over the summer months untouched.

It might be mud daubers - I couldn't find any information on wasp species in Turkey, but you could search in turkish. But they will build nests in some strange places.

This family of wasps is a mud nest builder, and world-wide

http://en.wikipedia.org/wiki/Sceliphron

Could be termites

Its part of a mud dauber nest.