Amateur botanists, please help in identifying this! It's not a cactus, but a close relative of Euphorbia trigona. (Thanks @rrikesh!)
Looks like a member of the large euphorbia family - which botanically may not be classified as a cactus. An easy to spot difference is the sap. When you cut a cactus, the sap will be clear and watery. However, the sap of an euphorbia species is white and sticky(sometimes poisonous). Your plant looks like a close relative of the Euphorbia trigona. Wait for it to flower, it will be easier to identify it.
@RikeshThank you! :D
You're welcome :)PS: Only the first letter of the family(genus) is written in block letters, ie, 'Euphorbia trigona' is correct, not 'Euphorbia Trigona'. It's a common mistake. Read about it here http://en.wikipedia.org/wiki/Binomial_nomenclature