I agree that it is most likely an Euphorbia, but what throws me is the posture of the stems and how they branch... My E. lactea and E. trigona are both upright in posture, and any branches are upright too. they do not have the right angle branches as shown in the picture. So I am not sure that it would be either trigona or lactea...
@GrowingCrazyLeonda that looks like a version of Mammillaria elongata.
